Flexible surface parameter measurement system for the muscular-skeletal system

ABSTRACT

At least one embodiment is directed to an insert for measuring a parameter of the muscular-skeletal system. The insert can be temporary or permanent. In one embodiment, the insert is prosthetic component for a single compartment of the knee. The insert comprises a support structure and a support structure respectively having an articular surface and a load bearing surface. The height of the insert can be less than 10 millimeters. At least one internal cavity is formed when support structures are coupled together for housing electronic circuitry, sensors, and the power source. The insert includes a flexible articular surface. Flexible articular surface transfers loading to sensors internal to the insert.

FIELD

The present invention pertains generally to a joint prosthesis, andparticularly to methods and devices for assessing and determining properloading of an implant component or components during jointreconstructive surgery and long-term monitoring of the muscular-skeletalsystem.

BACKGROUND

The skeletal system of a mammal is subject to variations among species.Further changes can occur due to environmental factors, degradationthrough use, and aging. An orthopedic joint of the skeletal systemtypically comprises two or more bones that move in relation to oneanother. Movement is enabled by muscle tissue and tendons attached tothe skeletal system of the joint. Ligaments hold and stabilize the oneor more joint bones positionally. Cartilage is a wear surface thatprevents bone-to-bone contact, distributes load, and lowers friction.

There has been substantial growth in the repair of the human skeletalsystem. In general, prosthetic orthopedic joints have evolved usinginformation from simulations, mechanical prototypes, and patient datathat is collected and used to initiate improved designs. Similarly, thetools being used for orthopedic surgery have been refined over the yearsbut have not changed substantially. Thus, the basic procedure forreplacement of an orthopedic joint has been standardized to meet thegeneral needs of a wide distribution of the population. Although thetools, procedure, and artificial joint meet a general need, eachreplacement procedure is subject to significant variation from patientto patient. The correction of these individual variations relies on theskill of the surgeon to adapt and fit the replacement joint using theavailable tools to the specific circumstance.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features of the system are set forth with particularity in theappended claims. The embodiments herein, can be understood by referenceto the following description, taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates an insert for measuring a parameter of themuscular-skeletal system in accordance with an example embodiment;

FIG. 2 illustrates an application of the insert sensing device inaccordance with an example embodiment;

FIG. 3 illustrates the insert placed in a joint of the muscular-skeletalsystem for measuring a parameter in accordance with an exampleembodiment;

FIG. 4 illustrates surfaces of the insert in accordance with an exampleembodiment;

FIG. 5 illustrates the insert and a plurality of shims in accordancewith an example embodiment;

FIG. 6 illustrates the lower support structure of the uni-condylarinsert in accordance with an example embodiment;

FIG. 7 illustrates the components of the insert in accordance with anexample embodiment;

FIG. 8 illustrates the assembled insert in accordance with an exampleembodiment;

FIG. 9 illustrates a cross-sectional view of the support structurehaving a flexible articular surface in accordance with an exampleembodiment;

FIG. 10 illustrates a cross-sectional view of an insert with aninflexible articular surface having an elastic flexible seal inaccordance with an example embodiment;

FIG. 11 illustrates a cross-sectional view of insert having a peripheralgroove in the support structure having the articular surface inaccordance with an example embodiment;

FIG. 12 illustrates the support structure having the load-bearingsurface including the port for sterilization in accordance with anexample embodiment;

FIG. 13 illustrates a seal having a membrane overlying the port inaccordance with an example embodiment;

FIG. 14 illustrates the seal in accordance with an example embodiment;

FIG. 15 illustrates the planar interconnect coupling to the sensors inaccordance with an example embodiment;

FIG. 16 illustrates a partial cross-sectional view of a sensor assemblyin accordance with an example embodiment;

FIG. 17 illustrates a cross-sectional view of the assembled insert inaccordance with an example embodiment;

FIG. 18 illustrates a block diagram of the components of an insert inaccordance with an example embodiment;

FIG. 19 illustrates communications system 1900 for short-range telemetryin accordance with an example embodiment;

FIG. 20 illustrates a communication network for measurement andreporting in accordance with an example embodiment; and

FIG. 21 illustrates a diagrammatic representation of a machine in theform of a computer system within which a set of instructions, whenexecuted, may cause the machine to perform any one or more of themethodologies discussed above.

DETAILED DESCRIPTION

Embodiments of the invention are broadly directed to measurement ofphysical parameters. More specifically, an electro-mechanical system isdirected towards the measurement of parameters related to themuscular-skeletal system. Many physical parameters of interest withinphysical systems or bodies are currently not measured due to size, cost,time, or measurement precision. For example, joint implants such asknee, hip, spine, shoulder, and ankle implants would benefitsubstantially from in-situ measurements taken during surgery to aid thesurgeon in fine-tuning the prosthetic system. Measurements cansupplement the subjective feedback of the surgeon to ensure optimalinstallation. Permanent sensors in the final prosthetic components canprovide periodic data related to the status of the implant in use. Datacollected intra-operatively and long term can be used to determineparameter ranges for surgical installation and to improve futureprosthetic components.

The physical parameter or parameters of interest can include, but arenot limited to, measurement of load, force, pressure, displacement,density, viscosity, pH, acceleration, and localized temperature. Often,a measured parameter is used in conjunction with another measuredparameter to make a qualitative assessment. In joint reconstruction,portions of the muscular-skeletal system are prepared to receiveprosthetic components. Preparation includes bone cuts or bone shaping tomate with one or more prosthesis. Parameters can be evaluated relativeto orientation, alignment, direction, or position as well as movement,rotation, or acceleration along an axis or combination of axes bywireless sensing modules or devices positioned on or within a body,instrument, appliance, vehicle, equipment, or other physical system.

In all of the examples illustrated and discussed herein, any specificmaterials, such as temperatures, times, energies, and materialproperties for process steps or specific structure implementationsshould be interpreted to be illustrative only and non-limiting.Processes, techniques, apparatus, and materials as known by one ofordinary skill in the art may not be discussed in detail but areintended to be part of an enabling description where appropriate. Itshould also be noted that the word “coupled” used herein implies thatelements may be directly coupled together or may be coupled through oneor more intervening elements.

Note that similar reference numerals and letters refer to similar itemsin the following figures. In some cases, numbers from priorillustrations will not be placed on subsequent figures for purposes ofclarity. In general, it should be assumed that structures not identifiedin a figure are the same as previous prior figures.

In the present invention parameters can be measured with an integratedwireless sensing module or device comprising an i) encapsulatingstructure that supports sensors and contacting surfaces and ii) anelectronic assemblage that integrates a power supply, sensing elements,an accelerometer, antennas and electronic circuitry that processesmeasurement data as well as controls all operations of energyconversion, propagation, and detection and wireless communications. Thewireless sensing module or device can be positioned on or within, orengaged with, or attached or affixed to or within, a wide range ofphysical systems including, but not limited to instruments, appliances,vehicles, equipments, or other physical systems as well as animal andhuman bodies, for sensing and communicating parameters of interest inreal time.

FIG. 1 is an illustration of an insert 100 for measuring a parameter ofthe muscular-skeletal system in accordance with an example embodiment.In general, insert 100 is a self-contained measurement system thatincludes an internal power source such as a battery or an inductivelycharged capacitor. In at least one embodiment, the system is a low costsystem that can be disposed of after use in a single intra-operativeprocedure. In the disposable embodiment, insert 100 cannot bere-sterilized nor can the power source be replaced without comprisingdevice integrity. Thus, operation is limited to a single use. In theintra-operative environment, insert 100 is disposed of similar to othermaterials or components exposed to biological matter. Alternatively,insert 100 can be a permanent implantable device or designed for asterilization process that allows re-use.

In the intra-operative example, insert 100 is a component of a jointreplacement system that facilitates movement of the muscular-skeletalsystem. In the illustration, the prosthetic insert 100 has a singlearticular surface 106 and a load-bearing surface 108 for supportingcompressive loads applied by the muscular-skeletal system in more thanone position. Insert 100 comprises a support structure 102 and a supportstructure 104 that form a housing or enclosure for the measurementsystem. Support structures 102 and 104 when coupled have one or morecavities therein that are isolated from an external environment. Supportstructures 102 and 104 respectively have articular surface 106 andload-bearing surface 108. The load-bearing surface 108 can be shaped tocouple with a prosthetic component. The height or thickness of insert100 can be adjusted by selection and attachment of a shim 118 that iscoupled to load-bearing surface 106. In one embodiment, load-bearingsurface 108 does not interface with a tibial prosthetic component. Shim118 can be also required as part of insert 100 assembly. Shim 118 can bedesigned to align with and be retained for a specific tibial prostheticcomponent. This is beneficial in providing flexibility in supportingmany different types of prosthetic component families with a singlemeasurement system. Shim 118 is a passive low cost component that can beprovided in many shapes and sizes. Alternatively, support structure 104can be shaped for a specific tibial prosthetic component such thatinsert 100 can only be mated to the tibial prosthetic component or afamily of prosthetic components. The shim 118 includes features 120extending from a surface 122. In the example, the features 120 arecylindrical columns. The cylindrical columns are inserted intocorresponding openings in the load-bearing surface 108 of supportstructure 104. An interference or clearance fit provides sufficientretention to hold shim 118 to support structure 104 while allowingremoval from insert 100 thereafter for shim replacement. The shim 118provides a surface substantially equal to the load-bearing surface 108for being received and retained by a tibial prosthetic component.Although a single shim 118 is shown, the system will provide multipleshims of varying height that can be used for height adjustment.

Typically, a joint replacement includes one or more prostheticcomponents that are coupled to surgically prepared bone surfaces. Oneprosthetic component has a surface that interfaces with the articularsurface 106 of the insert 100 allowing movement of the joint. Asmentioned previously, load-bearing surface 108 can interface with aprosthetic component attached to a prepared bone surface. Theload-bearing surface 108 typically does not support movement and has amuch larger surface area supporting the compressive loading applied bythe muscular-skeletal system. The articular surface 106 is low frictionand can absorb loading that occurs naturally based on situation orposition. In one embodiment, the articular surface 106 flexes underloading as will be disclosed in more detail below. The contact areabetween surfaces of the insert 100 and the prosthetic component can varyover the range of motion and the loading on the joint. Ligaments,muscle, and tendons hold the joint together and motivate the jointthroughout the range of motion. In a permanent implant example,articular surface 106 of the insert 100 will wear over time due tofriction produced by the prosthetic component surface contacting thearticular surface 106 during movement of the joint.

Insert 100 is an active device providing measurement capability having apower source, electronic circuitry, and sensors within the body of theprosthetic component. A printed circuit board is used as a mountingsubstrate and to couple the electronic components to form themeasurement system. Flexible interconnect is used to couple the sensorsto the electronic circuitry. The flexible interconnect will be discussedin more detail hereinbelow. In the example, insert 100 is usedintra-operatively to measure parameters of the muscular-skeletal systemto aid in the installation of one or more prosthetic components.Operation of insert 100 is shown as a uni-condylar knee insert toillustrate operation and measurement of one or more parameters such asloading and load position. Insert 100 can be adapted for use in otherprosthetic joints having articular surfaces such as the hip, spine,shoulder, and ankle. Insert 100 can also be used in a static environmentwithin the muscular-skeletal system.

In both intra-operative and permanent embodiments, insert 100 issubstantially equal in dimensions to a passive final prosthetic insert.In general, the substantially equal dimensions correspond to size andshape that allow insert 100 to fit substantially equal to the passivefinal prosthetic insert within the joint. In the intra-operativeexample, the measured loading and position of loading using insert 100as a trial insert would be substantially equal to the loading seen bythe final insert having equal heights. It should be noted that insert100 for intra-operative measurement can be dissimilar in shape or havemissing features that do not benefit the trial during operation. Insert100 is positionally stable throughout the range of motion similar to thefinal insert. In the example, the exterior structure of insert 100 isformed from support structures 102 and 104 coupled together. Supportstructures 102 and 104 have interior surfaces that couple together toisolate an interior cavity of insert 100 from an external environment.The interior surface 110 of support structure 104 interfaces with acorresponding interior surface of support structure 102. Surface 110 isa peripheral interior surface of support structure 104. The coupling ofinterior surfaces of support structures 102 and 104 can be permanent ortemporary. For example, support structures 102 and 104 can be fastenedby slot and tab for a temporary connection or welded/glued for apermanent connection. Support structures 102 and 104 have major surfacesthat are loaded by the muscular-skeletal system. Insert 100 is shown asa uni-condylar knee insert to illustrate general concepts but is notlimited to this configuration. Accelerated wear of the articular surfaceof the final insert can occur if the contact area is insufficient tosupport the load. Similarly, accelerated wear can occur if the contactlocation is not optimal to the insert. The contact position can alsovary depending on the position of the muscular-skeletal system. Insert100 measures the load and position of load applied by themuscular-skeletal system to the articular surface. The measurements areused to aid the surgeon in selection of the final insert and in makingadjustments such that the loading and position of load fall within apredetermined range found to optimize performance and wear of the jointsystem. The surgeon can use techniques such as soft tissue tensioning orbone modification with insert 100 in place to adjust the load magnitudeand position of the applied load using real-time feedback from thesensing system to track the result of each correction.

FIG. 2 illustrates an application of insert sensing device 100 inaccordance with an example embodiment. Insert sensing device 100 canalso be referred to as insert 100. In general, one or more naturalcomponents of the muscular-skeletal system are replaced when jointfunctionality substantially reduces a patient quality of life. A jointreplacement is a common procedure in later life because of wear, damage,or pain to the muscular-skeletal system. Joint reconstruction can reducepain while increasing patient mobility thereby allowing a return tonormal activity. In the example, insert 100 can intra-operatively assessa load on the prosthetic knee components and collect load data forreal-time viewing of the load over various angles of flexion. By way ofan integrated antenna, a compact low-power energy source, and associatedtransceiver electronics, the insert 100 can transmit measured load datato a receiver for permitting visualization of the level and distributionof load at various points on the prosthetic components. This can aid thesurgeon in making any adjustments needed to achieve optimal joint loadand balance. Insert 100 further includes a compact low-power energysource.

In general, an insert has at least one articular surface that allowsarticulation of the muscular-skeletal in conjunction with anotherprosthetic component. The insert is the wear component of a prostheticjoint and as used today is a passive component with no sensing ormeasurement capability. The insert is typically made of a solid block ofpolymer material that is resistant to wear, provides cushioning underloading, and is low friction. The block of polymer material is shaped tofit between other prosthetic components of the artificial joint. Onesuch polymer material used for inserts is ultra-high molecular weightpolyethylene.

A joint of the muscular-skeletal system provides movement of bones inrelation to one another that can comprise angular and rotational motion.The joint can be subjected to loading and torque throughout the range ofmotion. A natural joint typically comprises a distal and proximal end oftwo bones coupled by one or more articular surfaces with a low friction,flexible connective tissue such as cartilage. The natural joint alsogenerates a natural lubricant that works in conjunction with thecartilage to aid in ease of movement. Muscle, tendons, and ligamentshold the joint together and provide motivation for movement. Insert 100mimics the natural structure between the bones of the joint. In theexample, insert 100 has a single articular surface that interfaces withfemoral prosthetic component 204 that facilitates articulation of themuscular-skeletal system. A knee joint is disclosed for illustrativepurposes but insert 100 is applicable to other joints of themuscular-skeletal system. For example, the hip, spine, and shoulder havesimilar structures comprising two or more bones that move in relation toone another. In general, insert 100 provides parameter measurement overa range of motion of the muscular-skeletal system.

In the illustrated example, the insert 100 is a uni-condylar kneeinsert. A uni-condylar knee arthroplasty can be substantially lessinvasive than a total knee arthroplasty (TKA). People with damage to asingle knee compartment or less severe damage to one compartment arecandidates for uni-condylar knee arthroplasty. The joint components forthe uni-condylar reconstruction comprise the femoral prostheticcomponent 204, the insert 100, and a tibial prosthetic component 206.One difference that reduces the invasiveness of the uni-condylar surgeryis the bone preparation. The distal end of a femur 202 is prepared toreceive a femoral prosthetic component 204 that comprises a prostheticcondylar surface or partial condylar surface. Similarly, the proximalend of the tibia 208 is prepared to receive a tibial prostheticcomponent 206 for supporting and retaining insert sensing device 100.Femoral prosthetic component 204 and tibial prosthetic component 206 canbe both trial and permanent prosthetic components. Insert 100 can beused in both the trial and permanent prosthetic components to measure aparameter of the muscular-skeletal system such as loading magnitude andposition of loading. The primary surgical modification occurs in asingle knee compartment. The remaining knee compartment is untouched oronly slightly modified. The patient benefits substantially with the lessinvasive surgery through reduced pain, quicker recovery time, andpartial retention of natural joint function.

It should be noted that the external and interior volume of insert 100is more constrained in a uni-condylar application than a total kneearthroplasty. The total area and volume for the insert, electroniccircuitry, and sensors is greatly reduced in comparison to a dualcompartment device. The volume is less than 50% of the volume availablefor a dual compartment device. For example, the electronics can beshared between each compartment of a dual compartment device bymultiplexing between sensors. Moreover, the electronics can be placedbetween the knee compartments of a TKA insert where this region is notavailable for the uni-condylar arthroplasty. The insert 100 includeselectronic circuitry, a power source, telemetry, antenna, and sensorsall housed within and underlying the articular surface. The insert 100has a form factor substantially equal to a passive final uni-condylarinsert such that it can be used as an active final insert havingparameter measurement capability.

The height of insert sensing device 100 fits within the bone shapedregion of tibia 208 that includes tibial prosthetic component 206 of theknee joint. In the uni-condylar knee arthroplasty example, the surgeontargets a predetermined height or gap during the bone preparation. Inone embodiment, the self-contained measurement system comprising insert100 is less than or equal to 10 millimeters thick. In one embodiment, asmall form factor height for the insert 100 of approximately 6millimeters is achieved. Referring briefly to FIG. 1, support structure102 having the articular surface 106 and support structure 104 havingload-bearing surface 108 are coupled together to form a housing.Interior to the support structures is at least one interior cavity,which houses the self-contained measurement system. As shown, theprimary cavity is in the support structure 104. Flexible interconnectcouples three sensors to electronic circuitry in the cavity. A powersource such as a battery or capacitor powering the electronic circuitryis also in the cavity. A load plate 112 overlies the sensors, electroniccircuitry, and power source. The load plate 112 is aligned to thesupport structure 104 by alignment features 114 and couples to each ofthe sensors. A port 116 provides access to the interior of insert 100for sterilizing the cavity. The assemblage height measured from thebottom of the cavity of support structure 104 to the upper surface ofload plate measures approximately 4.5 millimeters. The combined wallthickness corresponding to the articular surface and load-bearingsurface is approximately 1.5 millimeters such that the height orthickness of insert 100 is approximately 6 millimeters.

Referring back to FIG. 2, the surgeon prepares the surfaces of femur 202and tibia 208 aligned to the mechanical axis of the leg having apredetermined gap height between the bone surfaces. The predeterminedgap height corresponds to the combined thickness of femoral prostheticcomponent 204, insert 100, and tibial prosthetic component 206. Trialprosthetic components are often used before final prosthetic componentsare installed to determine if the gap and cuts are appropriate.Adjustments are often made during the trial phase of the surgery.

In the illustration, a surgical procedure is performed to place thefemoral prosthetic component 204 onto a prepared distal end of the femur202. The femoral prosthetic component 204 is a single or partial condylecomponent. Similarly, a tibial prosthetic component 206 is placed onto aprepared proximal end of the tibia 208. The tibial prosthetic component206 is a tray or plate affixed to a planarized proximal end of a singlecompartment of the knee. The bone cuts are made to align the prostheticcomponents in relation to the mechanical axis of the leg to support anddistribute loading. The insert 100 is a third prosthetic component thatis placed between tibial prosthetic component 206 and the femoralprosthetic component 204. The three prosthetic components enable theprostheses to emulate the function of a natural knee joint. In theexample, insert 100 is used during surgery to take load and loadposition measurements that can be used to determine prosthetic componentfit and to make real-time adjustments to alter load magnitude, loadbalance, and load position to affect long-term joint performance.

As mentioned previously, insert 100 is inserted between femoralprosthetic component 204 and tibial prosthetic component 206. Thearticular surface of insert 100 contacts the surface of femoralprosthetic component 204. More specifically, a condylar surface of femur202 rotates on the articular surface of insert 100 when the tibia 208 ismoved in relation to femur 202. The tibial prosthetic component 206retains the insert 100 and has a corresponding surface that couples tothe load-bearing surface of the insert 100. Insert 100 is typically heldin a position corresponding to tibial prosthetic component 206 mountedto tibia 208. Typically, tibial prosthetic component 206 has a tray withsidewalls or other features for retaining insert 100 in a fixedposition. The muscle, tendons, and ligaments hold the joint together ina manner that applies a compressive force on the articular and loadbearing surfaces of insert 100 when installed correctly. The compressiveforce allows free movement of the joint while retaining the joint inplace over the range of motion and under various loadings. Measurementby insert 100 allows precise adjustment such that a force, pressure, orload is set during the trial phase of implantation or when the finalprosthetic components are installed. The quantitative measurements areused in conjunction with a surgeon's subjective feedback to ensureoptimal fit, position, loading of the prosthesis, and provideverification. The final insert will see a similar loading, balance, andposition of applied loading because the final insert and the trialinsert are dimensionally substantially equal. It should be noted thatinsert 100 is designed to be used in the normal flow of an orthopedicsurgical procedure without special procedures, equipment, or components.Dimensional equivalence of insert 100 with the final insert simplifiesthe procedure, allows access for adjustment, and provides compatibilityfor using the device as an active long-term measurement device toreplace the passive inserts being used today. Insert 100 as an activefinal insert can measure parameters of the muscular-skeletal system withsensors that provide quantitative data on joint status that can bereported to the patient and health care provider.

The insert 100 and the receiver station 210 form a communication systemfor conveying data via secure wireless transmission within abroadcasting range over short distances on the order of a few meters toprotect against any form of unauthorized or accidental query. In oneembodiment, the transmission range is five meters or less which willcover a typical operating room. In practice, it can be a shorterdistance 1-2 meters to transmit to a display outside the sterile fieldof the operating room. The transmit distance will be even shorter whendevice 200 is used in a prosthetic implanted component. Transmissionoccurs through the skin of the patient and is likely limited to lessthan 0.5 meters. A combination of cyclic redundancy checks and a highrepetition rate of transmission during data capture permits discardingof corrupted data without materially affecting the display of data.

As mentioned previously, insert 100 is substantially dimensionallyequivalent to a final insert from an operational perspective. The insert100 not only fits similarly within the joint as the final insert butalso is substantially equivalent from an operational perspective.Operational equivalency ensures that parameter measurements made byinsert 100 will translate to the final insert or be equivalent to whatis applied to the final insert by the muscular-skeletal system. In atleast one embodiment, insert 100 has substantially equal dimensions tothe final insert. There can be differences that are non-essential from ameasurement perspective between sensor 100 and the final insert. Thesubstantial equal dimensions ensure that the final insert when placed inthe reconstructed joint will have similar loading and balance as thatmeasured by insert 100 during the trial phase of the surgery. Thesubstantially equal dimensions also allow fine adjustment such as softtissue tensioning by providing access to the joint region. Moreover,passive trial inserts of different sizes are commonly used duringsurgery to determine the appropriate final insert. Thus, the procedureremains the same or similar to the surgeon but with the benefit ofquantitative real-time information. It can measure loads at variouspoints (or locations) on the femoral prosthetic component 204 andtransmit the measured data to a receiving station 210 by way of anintegrated antenna. The receiving station 210 can include dataprocessing, storage, or display, or combination thereof and provide realtime graphical representation of the level and distribution of the load.

As one example, the insert 100 can measure forces (Fx, Fy, and Fz) withcorresponding locations and torques (e.g. Tx, Ty, and Tz) on the femoralprosthetic component 204 and the tibial prosthetic component 206. It canthen transmit this data to the receiving station 210 to providereal-time visualization for assisting the surgeon in identifying anyadjustments needed to achieve optimal joint balancing.

In a further example, an external wireless energy source 225 can beplaced in proximity to the insert 100 to initiate a wireless powerrecharging operation. As an example, the external wireless energy source225 generates energy transmissions that are wirelessly directed to theinsert 100 and received as energy waves via resonant inductive coupling.The external wireless energy source 225 can modulate a power signalgenerating the energy transmissions to convey downlink data that is thendemodulated from the energy waves at the insert 100. As described above,the insert 100 is suitable for use as a trial or a permanent knee jointreplacement surgery. The external wireless energy source 225 can be usedto power the insert 100 during the surgical procedure or thereafter whenthe surgery is complete and the insert 100 is implanted for long-termuse to take periodic measurements of joint status.

In one system embodiment, the insert 100 transmits measured parameterdata to a receiving station 210 via one-way data communication over theup-link channel for permitting visualization of the level anddistribution of the parameter at various points on the prostheticcomponents. This, combined with cyclic redundancy check error checking,provides high security and protection against any form of unauthorizedor accidental interference with a minimum of added circuitry andcomponents. This can aid the surgeon in making any adjustments needed tooptimize the installation. In addition to transmitting one-way datacommunications over the up-link channel to the receiving station 210,the insert 100 can receive downlink data from the external wirelessenergy source 225 during the wireless power recharging operation. Thedownlink data can include component information, such as a serialnumber, or control information, for controlling operation of the insert100. This data can then be uploaded to the receiving system 210 uponrequest via the one-way up-link channel, in effect providing two-waydata communications over separate channels. Alternatively, two-waycommunication through a single channel can be used.

Separating uplink and downlink telemetry eliminates the need fortransmit-receive circuitry within the insert 100. Two unidirectionaltelemetry channels operating on different frequencies or with differentforms of energy enables simultaneous up and downlink telemetry.Modulating energy emissions from the external wireless energy source 225as a carrier for instructions achieves these benefits with a minimum ofadditional circuitry by leveraging existing circuitry, antenna,induction loop, or piezoelectric components on the insert 100. Thefrequencies of operation of the up and downlink telemetry channels canalso be selected and optimized to interface with other devices,instruments, or equipment as needed. Separating uplink and downlinktelemetry also enables the addition of downlink telemetry withoutaltering or upgrading existing chip-set telemetry for the one-waytransmit. That is, existing chip-set telemetry can be used for encodingand packaging data and error checking without modification yet remainscommunicatively coupled to the separate wireless power down-linktelemetry operation for download operations herein contemplated.Alternatively, insert 100 can be fitted with a standardized wirelesstransmit and receive circuitry such as Bluetooth, Zigbee, UWB, or otherknown wireless systems to communicate with receiver station 210.

As shown, the external wireless energy source 225 can include a powersupply 226, a modulation circuit 227, and a data input 228. The powersupply 226 can be a battery, a charging device, a capacitor, a powercoupling, or other energy source for generating wireless power signalsto power the insert 100. The external wireless energy source cantransmit energy in the form of, but not limited to, electromagneticinduction, or other electromagnetic or ultrasound emissions. In at leastone example embodiment, the wireless energy source 225 includes a coilto electromagnetically couple with an induction coil in insert 100 whenplaced in close proximity thereto. The data input 228 can be a userinterface component (e.g., keyboard, keypad, or touch screen) thatreceives input information (e.g., serial number, control codes) to bedownloaded to the insert 100. The data input 228 can also be aninterface or port to receive the input information from another datasource, such as from a computer via a wired or wireless connection(e.g., USB, IEEE802.16, etc.). The modulation circuitry 227 can modulatethe input information onto the power signals generated by the powersupply 226.

FIG. 3 illustrates insert 100 placed in a joint of the muscular-skeletalsystem for measuring a parameter in accordance with an exampleembodiment. In particular, insert 100 is inserted between femur 202 andtibia 208 for measuring a parameter. In the example, insert 100 includessensors to measure a force, pressure, or load applied by themuscular-skeletal system. Insert 100 is used to intra-operatively assessa compressive force applied by installed prosthetic components toload-bearing surfaces during the surgical procedure. The insert 100measures the load magnitude and position of load on the articularsurface while transmitting the measured data in real-time by way ofwireless data communication to receiver station 210 that can be used forreal-time visualization. This provides quantitative data to aid thesurgeon in making adjustments to achieve optimal joint loading and theposition of the applied load through use of soft tissue tensioning orbone shaping.

A proximal end of tibia 208 is prepared to receive tibial prostheticcomponent 206. Tibial prosthetic component 206 is a support structurethat is fastened to the proximal end of the tibia and is usually made ofa metal or metal alloy. In the example, the bone is prepared locally ina specific compartment. The remaining compartment is not modified and isleft in a natural state. The tibial prosthetic component 206 retains theinsert in a fixed position with respect to tibia 208. The lower majorsurface of insert 100 is a non-articulating load-bearing surface thatcouples to the major exposed surface of the tibial prosthetic component206 that is typically formed as a retention tray.

A distal end of femur 202 is prepared to receive femoral prostheticcomponent 204. Similarly, bone preparation of femur 202 occurs on thecondyle corresponding to the prepared bone surface of tibia 208. Thefemoral prosthetic component 204 is generally shaped having a condylarsurface that interfaces and articulates with insert 100. The bonepreparation of femur 202 and tibia 208 is aligned to the mechanical axisof the leg. The upper major surface of insert 100 is an articulatingsurface that couples with the condylar surface of the femoral prostheticcomponent 204 allowing movement of the tibia 208 in relation to femur202. The upper major surface of insert 100 is generally contoured tomate with the prosthetic condylar surface to maximize contact areathereby reducing wear. The lower major surface of insert 100 is aload-bearing surface for distributing loading. The loading on the lowermajor surface is typically lower than the load applied to the articularsurface of insert 100. In one embodiment, the height or thickness ofinsert 100 can be adjusted during surgery by adding one or more shims ofdifferent height. As shown, shim 118 removably attaches to the lowermajor surface of insert 100. Adding shims increases a height of insert100 thereby raising the compressive force applied by the joint to themajor surfaces of the insert 100 when inserted. Shim 118 when attachedto insert 100 has a major surface for interfacing with tibal prostheticcomponent 206 and being retained therein in a fixed position.

In general, prosthetic components are made in different sizes toaccommodate anatomical differences over a wide population range.Similarly, the insert 100 is designed for different prosthetic sizes andshapes. Internally, each sensing device will have similar electronicsand sensors. The mechanical layout and structure will also be similarbetween different sized units. After selecting appropriate sizedprosthetic components for the bone structure a remaining variable duringtrial insertion is the insert height. The height or thickness of insert100 is adjusted by one or more shims 118. In one embodiment, the gapbetween the femoral prosthetic component 204 and tibial prostheticcomponent 206 is approximately 10 millimeters. The insert 100 without ashim typically has a height less than or equal to 10 millimeters. Thesurgeon selects shim 118 based on the gap between the femur and tibialcuts after preparation of the bone surfaces. The insert 100 of the newpredetermined height is then inserted in the knee joint to interact withthe femoral prosthetic component 204 and tibial prosthetic component206. The surgeon may try changing the height or thickness usingdifferent shims before making a final decision on the appropriatedimensions of the final insert. Each trial by the surgeon can includemodifications to the joint and tissue. The insert 100 allowsstandardization for a prosthetic platform while providing familiarity ofuse and installation. Thus, the insert 100 can easily migrate from atrial insert to a final insert that allows long-term monitoring of thejoint.

In one embodiment, the insert 100 is used to measure a uni-condylarforce, pressure or load in a single compartment of the knee. Data frominsert 100 is transmitted to receiving station 210 via wired or wirelesscommunications. The surgeon can view the transmitted information on adisplay. The effect of an adjustment by the surgeon is viewed inreal-time with quantitative measurement feedback from insert 100. Thesurgeon uses the trial insert to determine an appropriate thickness forthe final insert that yields an optimal loading. The absolute loadingcan be monitored over the entire range of motion or in different pointsof flexion. In one example usage, insert 100 is removed and modifiedwith a shim if the absolute loading is found to be below a predeterminedrange. The predetermined range is based on statistical and clinicalevidence that produces a positive long-term joint replacement outcome.The height modified insert 100 is then re-inserted into the knee joint.Muscular-skeletal adjustments and shim adjustments can be made until theloading is within the predetermined range. It should be noted that finalinserts are available having equal or approximately equal heights andform factor to the shimmed insert 100. The measurement data can bestored for patient personal information or stored in a national databasefor long-term monitoring of the joint mechanics for improvement thereon.

The position or location of the applied force, pressure, or load occurson the articular surface can be measured by insert 100 allowing thesurgeon to view contact location of the femoral condyle to articularsurface over the range of motion on receiving station 210. The positionof load can be viewed along a plane or when one bone is rotated inrelation to another bone. Typically, it is not desirable for the loadingto be towards the outer edge of the articular surface. Insert 100 canidentify the position of loading on the articular surface is outside apredetermined area. An adjustment can be made by the surgeon to the boneor prosthetic components that affects where the point of contact occurson the articular surface or reduces the area of contact over the rangeof motion. The adjustments can be made in flexion or in extension andtracked by one or more accelerometers. The surgeon can then see inreal-time the effect of the modifications on the position of loading onthe articular surface over the range of motion. In one embodiment, thetrial components are fitted such that the load magnitude falls withinthe predetermined range and the position of load over the range ofmotion is within the predetermined area range. The surgeon can affectfurther change such as load balance by performing soft tissuetensioning. Soft tissue tensioning can increase or decrease thedifference in loading between the lateral and medial knee compartments.In one embodiment, the soft tissue tensioning can be performed withinsert 100 in place. The change produced by the soft tissue tensioningcan be monitored in real-time to show changes in load magnitude oninsert 100 due to the modification.

A passive final insert can be fitted between femoral prostheticcomponent 204 and tibial prosthetic component 206 after quantitativemeasurement data from insert 100 has been utilized to create anoptimized fit of the prosthetic components. The final insert has atleast one articular surface that couples to femoral component 204allowing the leg a natural range of motion. As mentioned above, thefinal insert has a wear surface that is typically made of a low frictionpolymer material. Ideally, the prosthesis has a loading, alignment, andbalance that mimic a natural leg. It should be noted that insert 100 canbe used as a final insert and operated similarly as disclosed herein toprovide long-term measurements via sensors therein. The wear surface ifactive insert 100 can comprise one or more layers of low frictionpolymer material such as ultra high molecular weight polyethylene. Thewear surface can be bonded or attached to a housing of insert 100 toform the articular surfaces. Alternatively, the upper and lower supportstructures that form a housing or enclosure can be molded or machinedfrom the low friction polymer material.

In one embodiment, insert 100 used intra-operatively is a low costdisposable system that reduces capital costs, operating costs,facilitates rapid adoption of quantitative measurement, and initiatesevidentiary based orthopedic medicine. In a second embodiment, amethodology of reuse can be implemented through sterilization. Twoembodiments, are disclosed herein where the cavity within the insert issterilized and where the cavity is not sterilized in a sterilizationprocess. In a third embodiment, can be incorporated in a tool,muscular-skeletal system, or the other prosthetic trial components thanthe insert. In a fourth embodiment, insert 100 can be a permanentcomponent of the replacement joint. Insert 100 can be used to provideboth short term and long term post-operative data on the implantedjoint. In a fifth embodiment, insert can be coupled to themuscular-skeletal system in a non-joint application for parametermeasurements. In all of the embodiments, receiving station 210 caninclude data processing, storage, or display, or combination thereof andprovide real time graphical representation of the level and distributionof the load. Alternatively, an indicator can be placed on insert 100that states whether the loading is high, low, or within thepredetermined range (e.g. different color LEDs). Receiving station 210can record and provide information generated by insert 100 to a securedatabase.

The insert 100 comprises a load-sensing platform 321, an accelerometer322, and sensing assemblies 323. This permits the insert 100 to assess atotal load on the prosthetic components as the joint is taken throughthe range of motion. The system accounts for forces due to gravity andmotion. In one embodiment, load-sensing platform 321 includes anarticular surface, a load plate, load-sensing assemblies 323, andelectronic circuitry. The accelerometer 322 of insert 100 measuresacceleration. Acceleration can occur when the insert is moved or put inmotion. Accelerometer 322 senses orientation, vibration, and impact. Inanother embodiment, the femoral component 204 can similarly include anaccelerometer 335, which by way of a communication interfacecommunicates to the insert 100, thereby providing reference position andacceleration data to determine an exact angular relationship between thefemur 202 and tibia 208. In one embodiment, sensing assemblies 323comprise at least three sensors coupled at predetermined locations tothe load plate. The load plate distributes the load applied to thearticular surface to sensing assemblies 323. Together the load sensingplatform 321, accelerometer 322, accelerometer 335, and sensingassemblies 323 provide quantitative information on relative position,position, load, and location of the applied load that can be used by thesurgeon for optimal installation of the prosthetic components.

Incorporating data from the accelerometer 322 assures accuratemeasurement of the applied load, force, pressure, or displacement byenabling computation of adjustments to offset external motion. Thiscapability can be required in situations wherein the body, instrument,appliance, vehicle, equipment, or other physical system, is itselfoperating or moving during sensing of load, pressure, or displacement.This capability can also be required in situations wherein the body,instrument, appliance, vehicle, equipment, or other physical system, iscausing the portion of the body, instrument, appliance, vehicle,equipment, or other physical system being measured to be in motionduring sensing of load, pressure, or displacement.

The accelerometer 322 can operate singly or as an integrated unit withthe sensing assemblies 323. Integrating one or more accelerometers 322within the sensing assemblages 323 to determine position, attitude,movement, or acceleration of sensing assemblages 323 enablesaugmentation of presentation of data to accurately identify, but notlimited to, orientation or spatial distribution of load, force,pressure, displacement, density, or viscosity, or localized temperatureby controlling the load and position sensing assemblages to measure theparameter or parameters of interest relative to specific orientation,alignment, direction, or position as well as movement, rotation, oracceleration along any axis or combination of axes. Measurement of theparameter or parameters of interest may also be made relative to theearth's surface and thus enable computation and presentation of spatialdistributions of the measured parameter or parameters relative to thisframe of reference.

In one embodiment, the accelerometer 322 includes direct current (DC)sensitivity to measure static gravitational pull with load and positionsensing assemblages to enable capture of, but not limited to,distributions of load, force, pressure, displacement, movement,rotation, or acceleration by controlling the sensing assemblages tomeasure the parameter or parameters of interest relative to orientationswith respect to the earths surface or center and thus enable computationand presentation of spatial distributions of the measured parameter orparameters relative to this frame of reference.

As mentioned previously, insert 100 can be used for other jointsurgeries; it is not limited to knee replacement implant or implants.Moreover, insert 100 is not limited to trial measurements. Insert 100can be incorporated into the final joint system to provide datapost-operatively to determine if the implanted joint is functioningcorrectly. Early determination or identification of problem can reducecatastrophic failure of the joint by bringing awareness to a problemthat the patient cannot detect. The problem can often be rectified witha minimal invasive procedure at lower cost and stress to the patient.Similarly, longer term monitoring of the joint can determine wear ormisalignment that if detected early can be adjusted for optimal life orreplacement of a wear surface with minimal surgery thereby extending thelife of the implant. For example, increasing load magnitude over time onthe articular surface is an indicator of improper wear and alignment. Ingeneral, insert 100 can be shaped such that it can be placed or engagedor affixed to or within load articular surfaces used in many orthopedicapplications related to the musculoskeletal system, joints, and toolsassociated therewith. Insert 100 can provide information on acombination of one or more performance parameters of interest such aswear, stress, kinematics, kinetics, fixation strength, ligament balance,anatomical fit and balance.

FIG. 4 illustrates surfaces of insert 100 in accordance with an exampleembodiment. Internal to insert 100 is a measurement system for measuringor monitoring the muscular-skeletal system. In the example, insert 100can be changed to have varying height or thickness and measure a force,pressure, or load. Insert 100 forms a housing for the measurement systemwhen support structures 102 and 104 are coupled together. The housingincludes a self-contained parameter measurement system. The height orthickness is adjusted by one or more shims. In the illustration, shim118 attaches to support structure 104 for increasing a height of insert100. Support structure 102 has an articular surface (not shown) allowingarticulation of the muscular-skeletal system. The housing formed bysupport structures 102 and 104 includes electronic circuitry, a powersource, and sensors comprising a complete self-contained system formeasuring a parameter of the muscular-skeletal system such as a force,pressure, or load applied to the articular surface. The insert 100 canhave a display to indicate the measured parameter or wirelessly transmitthe data for further data processing and enhanced user interface.

For illustrative purposes, insert 100 is a uni-condylar knee insert foruni-condylar knee reconstruction. The articular surface corresponds to asingle compartment of the knee. In one embodiment, the articular surfaceis concave for interfacing with a prosthetic femoral condyle surface. Amajor interior surface 402 of upper support structure 102 includes aregion 404 that interfaces with a load plate of the sensor assembly. Theregion 404 can include alignment features 408 for aiding in alignment ofsupport structure 104 to support structure 102. In the example, thealignment features 408 are holes or openings. The upper supportstructure 102 further includes a peripheral region 406 having a surfacethat interfaces with a corresponding surface of support structure 104.The peripheral region 406 and the corresponding surface of supportstructure 104 seal one or more cavities within insert 100 from anexternal environment when coupled together. The surfaces can be sealedmechanically or through the use of sealants. In the example, a sealantis used to attaches the peripheral surfaces of support structures 102and 104 together. The interior of structures 102 and 104 can behermetically sealed from the external environment using the sealant,welding, or bonding process. In one embodiment, the bond of theperipheral surfaces is so strong that the housing would be broken by anattempt to disassemble or separating support structures 102 and 104.This is beneficial when insert 100 is a disposable device for use in asingle application.

In the example, the uni-condylar tibial prosthetic component wheninstalled can have an exposed tray or surface for receiving andretaining insert 100. Insert 100 can have features that engage with thetibal prosthetic component to aid in retention. In one embodiment, theload-bearing surface 108 has a planar region that interfaces with aplanar region of the tibial tray of the tibial prosthetic component. Theinterface between the load-bearing surface 108 and the planar region ofthe tibial tray distributes the load over the area where the devicescouple together. Typically, the area where the tibial tray and insert100 couple together is greater than a corresponding area where theprosthetic femoral condyle couples to the articular surface of supportstructure 102. Thus, load per unit area on surface 108 is substantiallylower than the loading on the articular surface of support structure 102through distribution of the load over a larger area.

The minimum height of insert 100 comprises support structures 102 and104 without shim 118. As mentioned previously, insert 100 has beenfabricated having height or thickness less than 10 millimeters, which issuitable for most of the population requiring implants. Reducing theheight and form factor promotes further integration into tools,equipment, prosthetic components, and direct implants. In theuni-condylar application, insert 100 has been fabricated having a heightor thickness of approximately 6 millimeters. The sensing assembly withinthe interior of insert 100 has a height or thickness of less than 5millimeters. The overlying and underlying support surfaces of insert 100can have a thickness of approximately 0.5 millimeters in theintra-operative measurement device. Insert 100 is substantiallydimensionally equal in shape and size to a final insert. In the example,shim 118 is a passive device of insert 100 for adjusting insert height.In one embodiment, prior to inserting insert 100, the knee joint isprepared by a surgeon having trial or permanent femoral and tibialprosthetic components. As mentioned previously, the benefit of theuni-condylar surgery is that a knee compartment is kept in a naturalstate. The initial bone cuts and preparation are made on a singlecompartment, which is a much less invasive procedure. The uni-condylaroperation typically requires a smaller form factor when compared to adual compartment insert thus placing a premium on reducing height, area,and volume of insert 100. Insert 100 is used with both trial and finalfemoral and tibial prosthetic components. The gap left between thetibial and femoral prosthetic components is greater than or equal to theheight or thickness of insert 100 without shim 118.

A force can be applied to insert 100 to place the device between thefemoral and tibial prosthetic components. A peripheral region 412 ofsupport structure 104 has a surface that couples to the surface ofperipheral region 406 of support structure 102. The peripheral region412 is a sidewall that extends around the periphery of support structure104. Shim 118 couples to support structure 104 such that the loadbearing surface of shim 118 is similar to the load bearing surface ofsupport structure 104. The impact force applied to insert 100 insertsthe prosthetic component in the tray of tibial prosthetic component suchthat the tray retains peripheral region 412, a sidewall 414 of shim 118,or both. The muscle, ligaments, and tendons stretch to accommodateplacement of the insert 100 in the joint and retract once the prostheticcomponent is seated between the tibia and femur. The muscle, ligaments,and tendons apply a compressive force on the insert 100. Surgically, thegap between the trial or final prosthetic components is designed by thesurgeon to be approximately the height or thickness of insert 100 suchthat a shim can be used to generate a predetermined compressive force onthe articular surface of insert 100 after insertion. Insert 100 can beremoved from the tibal tray allowing shim replacement to adjust height.Shims of different heights or thicknesses, such as shim 118, are removedand replaced until an appropriate thickness for the final insert isselected using the quantitative measurements provided therewith. Theknee is placed in flexion to remove insert 100. In further embodiment,the height or thickness of insert 100 is selected to measure higher thanoptimal when inserted. In one embodiment, insert 100 is a trial insertthat is used to assess and select a final insert. Insert 100 isdimensionally substantially equal to the final insert allowing access tothe joint for further optimization processes. Soft tissue tensioning canbe used to adjust absolute magnitude of the uni-condylar prosthesis.Similarly, soft tissue tensioning can be used to adjust balance betweencompartments.

As disclosed above, shim 118 is attachable to the load bearing surface108 of insert 100. Shim 118 has major surfaces 122 and 416 that areload-bearing surfaces. Shim 118 has a predetermined height or thickness.The predetermined height or thickness of shim 118 is the distancebetween major surfaces 122 and 416. Major surface 122 of shim 118interfaces with load-bearing surface 108 of support structure 104. Inthe example, shim 118 can be temporarily attached to support structure104. In the embodiment, features 120 extend from major surface 122 andare shaped to fit in openings 410 of support structure 104. Althoughdescribed as cylindrical, the features can have shape and taper that aidin alignment, retention, and removal. For example, a T-shaped featurecould be used such that only a single orientation would allow couplingof shim 118 to support structure 104. Shim 118 is inserted into thecorresponding openings 410 in load-bearing surface 108 until the majorsurface 122 interfaces with load-bearing surface 108. In one embodiment,features 120 have a friction fit with openings 410. The height of insert100 is the combined height or thickness of support structure 102,support structure 104, and shim 118. In the example, the clearance orinterference fit allows shim 118 to be separated from support structure104 with little resistance. The use of shims allows rapid changing ofthe height of insert sensing device 100. The surgeon has both subjectiveand quantitative measurement to assess the installation. The feedback isprovided throughout the range of joint motion with insert 100 inserted.Finally, the insert 100 allows fine-tuning of the loading and balancewithin suggested predetermined ranges based on historical data. In oneembodiment, the predetermined ranges for measured loading would be basedon analysis of a large number of intra-operative and long-termquantitative measurements using sensored systems such as disclosedherein and related to operation of the prosthesis.

FIG. 5 illustrates insert 100 and a plurality of shims 520 in accordancewith an example embodiment. It should be noted that when discussing themeasuring system, the term insert 100 can include an attached shim butat a minimum comprises support structure 102 coupled to supportstructure 104 with active measurement circuitry therein. A sensingassembly 502 comprises at least one sensor and electronic circuitry. Inthe example, sensing assembly 502 is housed within insert 100 with apower source and a load plate for distributing a force, pressure, orload to multiple sensors. As shown, insert 100 includes sensors that arecoupled to the articular surface 106 through the load plate of sensingassembly 502. In one embodiment, three sensors are used to measure theload magnitude and the location where the load is applied to articularsurface 106.

The tibial prosthetic component 206 comprises a support surface 510,sidewalls 506, and features 508. As shown, tibial prosthetic component206 is used for a uni-condylar knee application. The support surface 510interfaces with a prepared bone surface of a proximal end of the tibia.Extending from the support surface 510 are features 508. Features 508locate and retain the tibial prosthetic component 206 to the preparedtibia bone surface in a fixed location. Features 508 fit intocorresponding openings of the prepared tibia bone surface. Sidewall 506is formed on the periphery of tibial prosthetic component 206 such thata cavity 504 is formed. Cavity 504 has a predetermined shape thatcorresponds to the shape of support structure 104 and shims 520. Theload-bearing surface 108 or the surface 522 of shims 520 interface withthe surface of the tray of tibial prosthetic component 206 when insertedtherein. An alternative to cavity 504 is one or more features on insert100 and tibial prosthetic component 206 that engage to retain insert 100in place when tibial prosthetic component 206 does not have sidewall506.

As shown, shims 520 comprises shims 512, 514, 516, and 518. In theexample, each shim has a different height or thickness. A system cancomprise more or less than the number of shims shown. Shims 520 includefeatures 120 for attaching to a load-bearing surface 108 of supportstructure 104. Support structure 104 has corresponding openings forreceiving features 120. In one embodiment, shims 520 comprise a solidmaterial such as plastic that does not deform or change height underloading. Alternatively, shims 520 can have cavities to reduce the amountof material used. For example, shim 520 can have hexagonal shapedcavities with the walls of the hexagonal cavities supporting theloading. The hexagonal wall structure would be more than sufficient tosupport and distribute the loading applied to insert 100 while reducingthe amount of material used. Each shim of shims 520 in combination withthe height of support structures 102 and 104 corresponds to an availablefinal insert thickness.

The appropriate device size is determined by loading and position ofload measured by sensing assembly 502. In the example, an appropriateheight is determined when the load magnitude and position of appliedloading on articular surface 106 is respectively within a predeterminedload magnitude range and a predetermined area range on articular surface106. Insert 100 is removed if the measurements are outside either range.The knee can be placed in flexion to allow access to remove insert 100.A shim can be used to increase or decrease height of insert 100 torespectively raise or lower the load magnitude reading. Also,modifications to the muscular-skeletal system or prosthetic componentscan be performed for adjustment to the area of applied loading or loadmagnitude. In one embodiment, once a suitable height has been identifiedinsert 100 is disposed of. The final insert of the identified height isinserted into the joint having the same height or thickness as the trialinsert. Fine adjustments such as soft tissue tensioning can be madeprior to or after the selection of the height of the final insert. Thefinal insert can be passive or have active circuitry for measuringparameters of the final insert or the knee joint region. In general, theload and position of load throughout the range of motion on the finalinsert is similar to that of the previously removed insert 100. Itshould be noted that the number of shims 520 in a kit provided forinstallation of a uni-condylar joint replacement can be more or lessthan shown in the illustration. The number of different heightavailability will depend on the needs of the specific muscular-skeletalapplication.

FIG. 6 illustrates lower support structure 104 of the uni-condylarinsert 100 in accordance with an example embodiment. An upper supportstructure (not shown) has at least one bearing or articular surface toallow movement of the muscular-skeletal system. The upper supportstructure fastens to the lower support structure 104 to form a sealedenclosure or housing. The sealed enclosure protects active circuitry ofinsert 100 for parameter measurement to aid in prosthetic installation,muscular-skeletal parameter measurement or long-term monitoring of areconstructed joint. The entire measurement system is self-containedwithin the upper and lower support structure. The insert 100 issubstantially equal dimensionally to a final passive insert. As shown,the measurement system fits within the dimensions of a uni-condylarprosthetic insert. In the example, the enclosure houses multiple sensorsfor measuring the magnitude and position of loading applied to acompartment of the knee.

The active system of the insert comprises sensors 602, interconnect 604,one or more printed circuit boards 622, electronic circuitry 618, and apower source 616. The electronic circuitry 618 is mounted on printedcircuit board 622. The electronic circuitry 618 comprises powermanagement circuitry, measurement circuitry, digital logic, parameterconversion circuitry, A/D converters, D/A converters, andtransmit/receive circuitry. In one embodiment, an application specificintegrated circuit (ASIC) 624 customized for muscular-skeletal parametersensing application is utilized. The ASIC 624 reduces the number ofcomponents that mount to printed circuit board 622. The integration ofcircuitry onto an ASIC eliminates unneeded circuitry, adds circuitryspecific to parameter measurement, reduces power consumption of themeasurement system, and reduces the sensing system form factor to a sizethat fits within a prosthetic component. Similarly, the printed circuitboard 622 reduces the form factor allowing for placement within auni-condylar insert. In one embodiment, the printed circuit board 622has multiple layers of interconnect for interconnecting components. Theprinted circuit board 622 can have components mounted on both majorsurfaces to further reduce the form factor. An antenna can also beformed on printed circuit board 622 for short-range transmission of themeasurement data. A fully populated printed circuit board 622 with powersource 616 has been manufactured that has a height or thickness equal toor less than 3.5 millimeters.

The power source 616 powers electronic circuitry 618 and sensors 602. Inone embodiment, the power source 616 comprises one or more batteries. Asshown, two batteries are coupled to the printed circuit board 616. Inone embodiment, the two batteries are coupled in series. In theintra-operative example, the measurement system is disposed of after thesurgery is completed or when the batteries are depleted. Alternatively,a rechargeable system can power electronic circuitry 618. The powersource 616 can be a rechargeable battery, capacitor, or other temporarypower source. The power source 616 can be electro-magnetically coupledto a remote power source for receiving charge. In the remote chargingexample, the power source 616 and power management circuitry enables themeasurement system for parameter measurement after sufficient charge isstored to perform a measurement process. It should be noted that thepower consumption reduction due to the ASIC enables the use ofrechargeable methodologies such as the capacitor. The capacitor providesthe further benefit of extended life and no chemicals when compared withbatteries for a long-term implant application such as joint monitoring.

In the example, the measurement system measures the load magnitude andload position that the muscular-skeletal system applies to the articularsurface of the upper support structure. The uni-condylar insert includesthree sensors 602 for load and position measurement. In one embodiment,each sensor 602 is a piezo-resistive film sensor. The resistance of apiezo-resistive film changes with an applied pressure. A resistance,voltage, or current corresponding to the piezo-resistive film under loadis measured. The measured resistance, voltage, or current is thencorrelated back to a pressure measurement. It should be noted thatsensor types such as continuous wave, pulsed, pulsed echo, strain gauge,polymer, mechanical, film, and mems to name but a few can also be used.The piezo-resistive sensor 602 being a film type sensor has a small formfactor from a depth perspective. The contact area of sensor 602 in oneembodiment is approximately 3.175 square millimeters. The load appliedto the articular surface is transferred through the load plate 112 tosensors 602 thereby compressing the film and modifying the resistancethereof. The amount of compression can vary depending on the selectedfilm type. In general, the change in height of the sensor assembly isnegligible measuring less than 0.2 millimeters for some sensor types. Inone embodiment, piezo-resistive film for measuring loading in auni-condylar application compresses approximately 0.508 millimeters overthe expected load range for an intra-operative application.

In a second embodiment, a transit time is correlated to the pressuremeasurement. Transit time measurements correspond to continuous wave,pulsed, and pulsed echo measurements. Transit time measurements can bevery accurate when taking a large number of measurements. An ultrasoniccontinuous wave or pulsed signal is propagated through a compressiblewaveguide. Loading on the insert compresses the compressible waveguidethereby changing the length of the waveguide. A change in lengthcorresponds to a change in transit time. The transit time can be relatedto a frequency by holding the number of waves in the compressiblewaveguide to a fixed integer number during a measurement sequence. Thus,measuring the transit time or frequency allows the length of thewaveguide to be precisely measured. The pressure can be calculated withknowledge of the length versus applied pressure relationship of thewaveguide.

The three sensors 602 underlie the bearing or articular surface of theupper support structure. Sensors 602 of each compartment are located atpredetermined positions on lower support structure 104. In the example,each sensor 602 overlies a corresponding pad region 608 as part ofsupport structure 104. The pad regions 608 can have a predetermined areathat couples to a corresponding sensor 602. Measurements from each ofthe sensors 602 are used to determine the location of applied loading tothe articular surface. The electronic circuitry 618 can takemeasurements sequentially or in parallel. The location and magnitude ofthe applied load is determined by analysis of the magnitudes from eachof the three sensors 602. The analysis includes a differentialcomparison of the measured loads. In general, the location of theapplied load is closer to the sensor reading the highest load magnitude.Conversely, the applied load will be farthest from the sensor having thelowest load magnitude. The use of sensors 602 at predetermined positionsallows the applied load location to calculated using the measured loadmagnitudes from each of sensors 602.

The support structure 104 further comprises peripheral surface 110, acavity 606, features 114, and a port 612. The peripheral surface 110mates with a corresponding surface of the upper support structure whencoupled together to form a housing. Features 114 extend from supportstructure 104. Features 114 align the support structure 104 to the uppersupport structure. The upper support structure has correspondingopenings to receive features 114. The cavity 606 underlies the articularsurface of the upper support structure. Cavity 606 can have features orstructures for aligning and retaining printed circuit board 622 inplace. The uppermost surface of printed circuit board 622 and componentsmounted thereon when placed in cavity 626 is approximately equal to orbelow a surface of pad regions 608.

As shown, pad regions 608 are placed in regions corresponding tovertexes of a triangle. In one example, two sides of the triangle formedby pad regions 608 are equidistant from the coronal plane having alength of approximately 19 millimeters. The third side of the triangleis approximately 38 millimeters in length. As mentioned previously,sensors 602 are placed on pad regions 608. The pad regions 608 can havefeatures to retain and align the sensors 602 in predetermined positions.An expanded view of pad region 608 and sensor 602 shows features 626 astabs on a periphery of pad region 608. Features 626 extend upward frompad region 608. Sensor 602 has notches 628 corresponding to features626. Sensor 602 can be placed on pad region 608 to engage with features626 to retain and align sensor 602 to pad region 608, interconnect 604,and load plate 112. In one embodiment, sensors 602 have a predeterminedarea for coupling to the articular surface and sensing a load appliedthereto. The pad regions 608 have an area equal to or larger than thepredetermined area of sensors 602. The predetermined area of sensors 602is selected to distribute the load over sufficient area for reliablesensing, provide a measurable signal (e.g. voltage, current, resistance)over the loading range, and have the sensitivity for precisemeasurement. The predetermined area and location is sufficiently smallto allow accurate identification of the load location based on themeasurements from the three locations.

The interconnect 604 overlies a portion of the printed circuit board 622and portions of sensors 602. The interconnect 604 includes cut awaysections for receiving features 114. Features 114 couple through the cutaway sections of interconnect 604 thereby aligning and retaining thestructure. Conductive traces on interconnect 604 interface withconductive traces on sensors 602 for coupling to electronic circuitry618. A connector 620 is coupled to components on printed circuit board622. A tab 610 having conductive traces is inserted into connector 620for coupling electronic circuitry 618 to sensors 602. The load plate 112overlies the interconnect 604 and sensors 602. The load plate couples tosensors 602. In the example, load plate 112 is approximately triangularin shape. Load plate 112 distributes the force, pressure, or loadapplied to the articular surface to sensors 602. Support structure 104further includes a port that will be disclosed hereinbelow. The port isa path for providing a sterilizing gas into cavity 606. A seal 614includes a gas permeable membrane such that gas can pass into cavity 626but liquid and solids are blocked from entering.

FIG. 7 illustrates the components of insert 100 in accordance with anexample embodiment. Support structure 104 includes pad regions 608 thatsupport sensors 602. In the example, three pad regions 608 and threecorresponding sensors 602 are used to determine location of applied loadto the articular surface 106 of insert 100. In one embodiment, the padregions 608 have a predetermined area and can include features to retaina sensor. The predetermined area is selected to provide sufficient areafor monitoring a signal magnitude and differential signal changes withinthe resolution required for the muscular-skeletal application. Padregions 608 are a predetermined height above the load-bearing surface108 of support structure 104. The predetermined height is chosen toensure that the electronic circuitry 618 does not interfere with theapplication of load to the articular surface 106 as will be discussed ingreater detail hereinbelow. In one embodiment, a sidewall directs andretains the sensor 602 in the predetermined area and in a predeterminedorientation. The features can orient the sensor lead to allow couplingwith interconnect 604 during an assembly process.

In the uni-condylar example, the electronic circuitry 618 partially orcompletely underlies a region where loading is applied to the articularsurface 106. Electronic circuitry 618 is located centrally withinsupport structure 104 in the cavity 606. The electronic circuitry 618 ismounted to and interconnected by patterned metal interconnect on printedcircuit board 622. The power source 616 and connector 620 are mounted toprinted circuit board 622. In the example, the power source 616comprises batteries that power the measurement system for a singleapplication. The printed circuit board 622 and cavity 606 can have apredetermined shape that allows a singular orientation for placementtherein. Cavity 606 can include support structures and retainingfeatures to support and retain electronic circuitry 618 in place. Toreduce form factor the printed circuit board 622 or components mountedthereon can contact an interior surfaces of the cavity 606.Alternatively, the printed circuited board 618 and components have asmall gap between the interior surfaces of cavity 606. In oneembodiment, the pad regions 608 are co-planar to one another at thepredetermined height above the load-bearing surface 108 of supportstructure 104. The uppermost surface of printed circuit board 622,electronic circuitry 618, and power source 616 is below sensors 606 whenplaced in cavity 606. More specifically, under maximum compression (ormaximum loading) of sensors 602 the interconnect 604 or load plate 112would not make contact with the measurement system electronics.Similarly, if the pad regions 608 were not co-planar to one another, thesystem electronics would be below the sensor 602 having the pad region608 of the lowest height above the load-bearing surface 108.

A sensing assembly stack of insert 100 comprises the load plate 106,sensors 602, and pad regions 608. The pad regions 608 are arranged to beat the vertexes of a triangle. In the example, the majority of cavity606 is between and within the bounds of the triangle defined by padregions 608. As mentioned previously, the electronic circuitry 618,power source 616, and printed circuit board 622 are placed in cavity606. The sensors 602 are placed on pad regions 608. In the example,sensors 602 are piezo-resistive film sensors that changes resistance dueto a pressure applied thereto. Interconnect 604 overlies and couples toeach sensor 602. As mentioned previously, the pad regions 608 areco-planar to one another. The interconnect 604 can be flexible but isplanar to connect to sensors 602. At least a portion of interconnect 604overlies electronic circuitry 618, printed circuit board 622, and powersource 616. The alignment features 114 couple through openings ininterconnect 604 to align interconnect 604 to sensors 602. The tab 610of interconnect 604 is a flexible connector. Tab 610 couples toconnector 620 on printed circuit board 622 thereby coupling sensors 602to electronic circuitry 618. The load plate 112 is coupled to aninterior of surface of the support structure 102. The alignment features114 couple through openings 702 to align load plate 112 to sensors 602.The vertices of load plate 112 couple to sensors 602. At least a portionof load plate 112 overlies electronic circuitry 618, printed circuitboard 622, and power source 616. Finally, an interior surface of supportstructure 102 couples to load plate 112. In one embodiment, the coupledinterior surface of support structure 102 is shaped similar to that ofload plate 112. The interior surface of support structure 102 includesopenings to receive alignment features 114 to align support structure102 to support structure 104. The surface 406 of support structure 102and the surface 110 of support structure 104 are coupled together eitherpermanently or temporarily to seal the cavity 606 and components thereinfrom an external environment.

In general, a load applied to the articular surface 106 couples throughsupport structure 102 to the interior surface where it is applied to thesensing assembly stack. The load plate 112 distributes loading from theinterior surface of support structure 102 to the three sensors 602. Eachsensor 602 provides a measurement to electronic circuitry 618 throughinterconnect 604. The magnitude of the applied load to articular surface106 is calculated from the three measurements. Similarly, the locationwhere the load is applied on the articular surface 106 is calculatedusing each sensor measurement and the location of each sensor relativeto articular surface 106.

FIG. 8 illustrates assembled insert 100 in accordance with an exampleembodiment. Components from FIG. 7 will also be referred to in thedescription. Insert 100 is substantially equal in dimensions to apassive final insert and can be used similarly. The passive final inserthas no measurement capability and is a long-term or permanent insert fora muscular-skeletal joint. Insert 100 can be used intra-operatively toaid in the assessment, installation, and optimization of a joint of themuscular-skeletal system or as an active final insert for providingjoint information long-term. For example, insert 100 as an active finalinsert can be used to measure insert wear, loading, position of loading,infection, and joint range of motion. In one embodiment, insert 100 isactivated by charging a capacitor for powering the measurement system.The capacitor holds sufficient charge to perform the requiredmeasurement sequences and wirelessly send the data to an appropriatesource for analysis. The quantitative loading and position of loadingmeasurements can be used if a misalignment or contact surface issuearises that could cause accelerated joint failure. Knowledge of changesin the joint can be used to correct the joint problems before acatastrophic failure or major invasive surgery is required.

As shown, support structure 102 and support structure 104 are fastenedtogether forming active insert 100. The major exposed surfaces ofsupport structures 102 and 104 are respectively articular surface 106and load-bearing surface 108. Although shown as a uni-condylar kneeinsert, the form factor disclosed herein allows the measurement systemto be used in other inserts such as the hip, spine, ankle, and shoulderto name but a few. The measurement system can also be placed in themuscular-skeletal system or in a tool or equipment. The coupling ofsupport structures 102 and 104 can utilize a variety of techniques suchas mechanical, adhesives, and welding. The coupling of the structurescan be temporary or permanent. In the intra-operative example, a strongadhesive holds the peripheral interior surfaces that align and matetogether. The adhesive seals the internal cavity of insert 100 from anexternal environment. In one embodiment, the seal is hermetic such thatsolids, liquids and gasses cannot enter into the at least one interiorcavity of insert 100. Separating support structures 102 and 104 can be adestructive process where support structures 102 and 104 can break orfracture rendering the device useless for the instance where it is adisposable device for a single application.

In one embodiment, at least one load-bearing surface of insert 100comprises polycarbonate. The polycarbonate load-bearing surface can bearticular surface 106, load-bearing surface 108, or both. The use ofpolycarbonate or other material having similar properties for supportstructures 102 and 104 is suitable for intra-operative measurements. Inthe example, support structures 102 and 104 both comprise polycarbonate.The use of polycarbonate provides the benefit of promoting wirelesscommunication. Other joint components are often made of metal. The metalcan act as a shield when insert 100 is placed in the joint therebyreducing the signal strength of the transmission. The use of a polymersuch as polycarbonate is transmissive to the radio frequency signalsbeing used by insert 100 for transmitting and receiving.

In general, articular surface 106 can flex to increase load coupling tothe load plate. Allowing the articular surface to flex decouples loadtransfer through the periphery surface of support structure 102 thatcouples to support structure 204. Allowing articular surface 106 to flexdirects the applied load to the load plate 112. More specifically, loadplate 112 transfers and distributes the force, pressure, or load fromthe internal surface of support structure 102 to sensors 602 atpredetermined locations. Sensors 602 are internal to the insert 100. Thepredetermined locations where sensors 602 are located correspond andrelate to articular surface 106. Conversely, load-bearing surface 108 isa rigid surface that does not flex but has a large surface area fordistributing load to a prosthetic component. In general, the load perunit area on load-bearing surface 108 is less than the load per unitarea on articular surface 106. Moreover, the flexure of articularsurface 106 ensures that loading thereon is directed principally to theload plate and not to the peripheral surface coupled to supportstructure 104. Correction or calibration can be used to further increaseaccuracy to take into account any applied articular load that isdistributed through the peripheral surface of support structure 102 whencompared to a reference. Allowing flexure of articular surface 106 andrelying on load plate 112 for stiffness promotes a compact form factor.

A load applied to articular surface 106 is transferred through theflexible structure to an interior surface of support structure 102. Theload plate 112 is coupled to the interior surface of support structure102 for receiving the applied load. The load plate 112 is a rigidstructure that does not flex. In one embodiment, load plate 112comprises a metal such as steel or aluminum. The load plate 122 thendistributes the loading to each sensor 602 proportionate to the locationof the applied load to articular surface 106. The magnitude of theapplied load to articular surface 106 can be calculated from themeasured magnitudes of each sensor 602. The location of the load appliedto articular surface 106 is calculated by knowing the positions of eachsensor in relation to the articular surface 106 and the differentialmagnitudes between each sensor measurement.

In general, support structures 102 and 104 form an enclosure whencoupled together for housing the measurement system that can include oneor more sensor types that can measure different parameters of themuscular-skeletal system. The enclosure is sufficiently rigid to supportloading applied by the joint without deflecting. Conversely, thearticular surface 106 of support structure 102 can flex to supportforce, load, and pressure measurement.

Referring briefly to FIG. 9, the articular surface 106 can flex underthe loading. In one embodiment, the material of articular surface 106 ismade sufficiently thin to allow flexing under loading applied by themuscular-skeletal system in the joint application. Support structure 102includes a peripheral region 406 that couples to surface 110 of supportstructure 104. The flexible surface of articular 106 couples the appliedload to the rigid load plate 112 while directing little or no loadingthrough the peripheral region 406 of support structure 102 that couplesto the surface 110 of support structure 104. In the example, supportstructure 102 comprises a polymer material such as polycarbonate. Theinterior surface underlying articular surface 106 couples to load plate112. Other areas of support structure 102 do not flex substantially. andcan be rigid such that no flex occurs. Referring back to FIG. 8, thesensing assembly stack couples to the articular surface 106 and issupported by the load-bearing surface 108 of support structure 104. Theload plate 112, pad regions 608, and interconnect 604 do not compress orcompress slightly by the force, pressure, or load applied to articularsurface 106. Load plate 112, pad regions 608, and interconnect 604supports and transfers the force, pressure, or load to sensors 602. Inthe example, sensor 602 is a piezo-resistive film sensor that changesresistance as a function of loading applied thereto. In general, thechange in thickness of the piezo-resistive film over the pressuremeasurement range required for an intra-operative load sensingapplication can be supported by flexing of articular surface 106 suchthat the load is applied to the load plate 112 and not other regions ofsupport structure 102.

Referring to FIG. 10, an alternate structure and method for directingthe load applied to articular surface 106 is illustrated. Supportstructure 102 includes a non-flexing articular surface 106. A flexiblegasket 1002 is coupled to the peripheral surfaces of support structures102 and 104. The flexible gasket 1002 couples between surfaces 406 and110 respectively of support structures 102 and 104. Surfaces 406 and 110can be shaped to retain flexible gasket 1002. For example, surfaces 406and 110 can be concave to support a curved surface of flexible gasket1002. Flexible gasket 1002 seals insert 100 thereby isolating the cavity606 from an external environment. The support structures 102 and 104 arecoupled together by a latch mechanism. The latch mechanism comprises afeature 1004 and a feature 1006 respectively extending from supportstructure 102 and support structure 104. Latch surfaces of features 1004and 1006 interface and retain structures 102 and 104 when flexiblegasket 1002 is compressed such that the features interlock together.Support structures 102 and 104 can respectively include more than onefeature 1004 and 1006 for retaining the housing together. Flexiblegasket 1002 comprises an elastic material that exerts an outward forceon features 1004 and 1006 such that the retaining interface are forciblyheld together. The flexible gasket 1002 can further flex or compresswhen a force is applied to articular surface 106 allowing the articularload to be applied to the sensor assembly stack for accuratemeasurement.

Referring to FIG. 11, an articular surface 106 modified to be flexibleis provided. Similar to that described above, articular surface 106 ismade flexible to direct loading to a load plate and to minimize loadcoupling through the surfaces 406 and 110 respectively of supportstructures 102 and 104. Surfaces 406 and 110 are coupled together at theperiphery of insert 100. A groove 1102 is cut in the periphery ofsupport structure 102. Groove 1102 allows articular surface 106 to flexwhen a load is applied. Articular surface 106 is rigid with little or noflexibility without groove 1102. In one embodiment, the groove iscircumferential around the periphery of support structure 102. Thegroove 1102 is placed interior to the surfaces 406 and 110 within insert100 thereby providing further decoupling.

Referring back to FIG. 8 a method of transferring a force, pressure, orload applied by the muscular-skeletal system is supported by theembodiment disclosed herein. The steps disclosed herein can be performedin any order or combination. In the method, a force, pressure, or loadof the muscular-skeletal system is measured. An insert 100 is insertedin a joint of the muscular-skeletal system. The insert 100 has anarticular surface 106 and a load-bearing surface 108. In a first step,the muscular-skeletal system applies a compressive force, pressure, orload to insert 100. In one embodiment, the measurement system isself-contained within insert 100, is substantially equal dimensionallyto a passive final insert, measures load magnitude, and load positionapplied to articular surface 106. The articular surface 106 of supportstructure 102 allows movement of the joint of the muscular-skeletalsystem. In the example, the articular surface 106 interfaces with aprosthetic component coupled to a first bone. The support structure 104has a load-bearing surface 108 that interfaces with a prostheticcomponent coupled to a second bone. The load-bearing surface 108 isretained to the second bone in a fixed relationship to support thedistribution of loading thereto.

In a second step, the force, pressure, or load applied to the articularsurface 106 is transferred from articular surface 106 to an interiorsurface of support structure 102. In general, the articular surface 106,and the interior surface comprise a common substrate of supportstructure 102. In a third step, the force, pressure, or load is coupledto sensors 602 housed within the cavity 606 of insert 100. The sensors602 are at predetermined positions within insert 100 that correspond tolocations on articular surface 106. The articular surface 106 flexesunder loading to ensure transfer of the load to the sensors 602.

In a fourth step, flexing is achieved by forming the substrate or layerhaving the articular surface 106 and the interior surface having athickness that allows flexing to direct the loading to the sensors 602for measurement. The thickness can vary depending on the material usedto form support structure 102 and the force, pressure, or load appliedthereto. Alternatively, in a fifth step, flexing is achieved by formingthe peripheral groove 1102 in support structure 102. In one embodiment,the peripheral groove 1102 is adjacent to a boundary of articularsurface 106. For example, the peripheral groove 1102 is between thearticular surface and the structural wall of support structure 102having surface 406. The groove 1102 allows the articular surface 106 toflex under loading thereby directing the force, pressure, or load to theinterior surface of support structure 102 and sensors 602.

In a sixth step, the electronic circuitry 618 for measuring the force,pressure, or load is housed in insert 100. At least one cavity 606 isformed internal to insert 100 when support structures 102 and 104 arecoupled together. In a seventh step, the support structures 102 and 104are sealed together such that the electronic circuitry 618 and sensors602 are isolated from an external environment. In the example, surfaces406 and 110 respectively of support structures 102 and 104 are coupledtogether by an adhesive. Surfaces 406 and 110 are attached and sealedaround the entire periphery. The adhesive forms a bond to surfaces 406and 110 that fractures or breaks support structures 102 and 104 duringan attempt to separate.

In an eighth step, each sensor 602 is supported by a pad region 608 ofsupport structure 104. The pad regions 608 are at predeterminedlocations corresponding to articular surface 106. Each pad region 608couples to and is support by the load-bearing surface of supportstructure 104. In the example, at least a portion of the electroniccircuitry 618 is housed between the sensors 602. In a ninth step, thesensors 602 are coupled to the articular surface through the load plate112. The load plate couples to the interior surface of support structure102. The support structure 104 includes at least one alignment feature114. The alignment feature 114 aligns the load plate 112 to the interiorsurface of support structure 102.

The measurement system for measuring a parameter of themuscular-skeletal system disclosed herein is sterilized prior to beingused intra-operatively or as an implant. The description of thesterilization process will refer to components illustrated in FIGS. 7and 8. Insert 100 is a joint prosthetic component for themuscular-skeletal system having articular surface 106 and load-bearingsurface 108. The articular surface 106 and load-bearing surface 108 arerespectively major surfaces of support structures 102 and 104. Thearticular surface 106 interfaces with the muscular-skeletal system tosupport joint movement. Support structures 102 and 104 coupled togetherform an enclosure for a self-contained measurement system. The cavity606 within insert 100 contains electronic circuitry 618 that isoperatively coupled to at least one sensor 602. Support structures 102and 104 are sealed together such that the cavity 606 is isolated fromthe external environment. The seal can be mechanical, a weld, oradhesives, which hold and seal structures 102 and 104 together. In oneembodiment, structures 102 and 104 are coupled together to form ahermetic seal. In one embodiment, insert 100 is sterilized prior to use.The sterilization process sterilizes interior surfaces and exteriorsurfaces of insert 100. For example, articular surface 106, load-bearingsurface 108, sidewall surfaces, and other exterior surfaces of insert100 are sterilized. Similarly, the cavity 606 and the componentscomprising the measurement system are sterilized. The sterilizationprocess comprises exposing the exterior and interior of insert 100 to asterilization agent. In one process, insert 100 is exposed to asterilization gas, sterilized, and packaged in a sterile container orpackage. The process takes place within a clean room environment. Thecontainer or packaging maintains sterility of insert 100 until it isused. Typically, the sterile container is opened immediately prior touse within the sterile field of an operating room thereby ensuring thesterile status of insert 100 before contact to a patient.

Referring briefly to FIG. 12, the port 612 is shown in support structure104. The port 612 couples the external environment to cavity 606 ofinsert 100. The sterilization gas enters into cavity 606 through theport 612. The components of FIGS. 6 and 7 can be referenced in thedescription of FIGS. 12-14. Seal 614 can include a membrane that is abarrier between the port and cavity 606. Seal 614 prevents the ingressof solids or liquids into the cavity 606. Referring briefly to FIG. 13,seal 614 is shown briefly coupled to an interior surface of supportstructure 104. Although not shown, one or more features on supportstructure 104 can retain an O-ring portion of seal 614 to the interiorsurface forming a seal. For example, the features can compress the ringportion of seal 614 to the interior surface of support structure 104when support structures 102 and 104 are fastened together.

FIG. 14 illustrates seal 614 in accordance with an example embodiment.In one embodiment, seal 614 is shaped as an o-ring with a gas permeablemembrane 1302. A circumferential ring portion 1306 of seal 614 iscompressed against the interior surface of support structure 104adjacent to the port to seal the cavity housing the electronic circuitryfrom the ingress of liquid or solid matter from the externalenvironment. Gas permeable membrane 1302 is located interior to ringportion 1306. Gas permeable membrane 1302 can be exposed tosterilization gas during the sterilization process. In one embodiment,membrane region 1302 can comprise silicone, which is a gas permeablematerial that prevents liquid or solid matter from entering into cavity606 through port 612. Silicone is compliant, conformal, compressible,and elastic making it suitable for interfacing and sealing to a surface.Gas permeable membrane 1302 has a diameter 1304 that determines a rateof diffusion of the sterilization gas into the interior cavity 606. Inone embodiment, the sterilization process is a timed event thatsterilizes the interior and exterior surfaces of insert 100. Thethickness and predetermined area of interior membrane region 1302 ofseal 614 is selected to ensure that sufficient gas enters into cavity606 for the time period of the sterilization process.

A method of providing intra-operative muscular-skeletal parametermeasurement is supported by the embodiment disclosed hereinabove. Thesteps disclosed herein can be performed in any order or combination. Ina first step, electronic circuitry 618 is housed within the insert 100.Insert 100 is a self-contained measurement system having electroniccircuitry 618, sensors 602, and a power source 616 within a cavity 606.The cavity 606 is isolated from the external environment. In particular,insert 100 is sealed such that liquids and solids from the externalenvironment cannot enter into cavity 606 to contaminate or affect theperformance/reliability of the measurement system. Insert 100 hasarticular surface 106 and load-bearing surface 108 for interfacing withnatural or prosthetic components of a joint. Articular surface 106allows movement of a first bone in relation to a second bone. Insert 100is substantially dimensionally equal to a final passive insert. In asecond step, insert 100 is sterilized. The exterior surfaces and cavity606 of insert 100 are sterilized.

In one embodiment, a sterilization process comprises exposing insert 100to a sterilization gas. The sterilization gas kills biologicalcontaminants that may be on insert 100 after manufacture and assembly.The insert 100 is exposed to a predetermined gas concentration for apredetermined length of time that ensures sterility. In a third step,the sterilizing gas couples through port 612 into cavity 606 forsterilizing interior regions and components within insert 100. In afourth step, the insert includes a barrier to liquids and solids whenassembled. The barrier prevents the liquids and solids from enteringinto the cavity 606 of insert 100. A seal 614 is placed between port 612and cavity 606. The seal 614 covers and seals port 612. The seal 614 ispermeable to gas but non-permeable to liquids and solids. Aftersterilization, insert 100 can be subjected to an evacuation process thatremoves or reduces the sterilization gas in or on the device. In a fifthstep, insert 100 can be placed in a container or package that maintainssterility and prevents contamination prior to surgery.

Insert 100 can be used intra-operatively to provide quantitativemeasurements data on the muscular-skeletal system or implanted into themuscular-skeletal system to provide long-term or periodic measurements.In the intra-operative or implant example, the insert 100 is provided inthe operating room to the surgical team. In a sixth step, the sterilepackaging is opened within a sterile field of the operating room. In aseventh step, the insert 100 is removed from the packaging and insertedinto a joint of the muscular-skeletal system. Insert 100 can be enabledfor measurement prior to insertion or after the device is installed. Inan eighth step, the enabled insert 100 measures a parameter of themuscular-skeletal system. In the example, the data measured by insert100 is wirelessly sent to a receiving device. The receiving device canbe equipment, tools, a processor, computer, digital logic, a display, adatabase, or other devices for using the parameter measurement data. Inthe operating room, the data can be continuously displayed allowing thesurgical team to see the information over a range of joint motion or asmodifications are being performed. In one embodiment, insert 100 whenused intra-operatively is a low cost disposable measurement device. Thelow cost and ease of use promotes rapid adoption. Moreover, insert 100provides the substantial benefit of providing quantitative data tosupplement the subjective nature of orthopedic procedures done today. Ina ninth step, insert 100 is disposed of after the surgery has beencompleted when used intra-operatively.

In an alternate embodiment, insert 100 does not have port 612 and seal614. Insert 100 operates similarly as self-contained measurement systemfor measuring a parameter of the muscular-skeletal system as describedhereinabove. Insert 100 has articular surface 106, load-bearing 108, andinterior cavity 606 housing electronic circuitry 608. In general, thecavity 606 is not sterilized during the sterilization process beforepackaging. The cavity 606 is sealed and isolated from an externalenvironment such that solids, liquids, and gases cannot enter or leavecavity 606. In one embodiment, the cavity 606 is hermetically sealed.The components comprising insert 100 are cleaned and assembled in asterile environment such that contaminants are kept to a minimum. Afterassembly, the interior cavity 606 is no longer accessible. Subsequently,insert 100 undergoes an extensive sterilization process where theexternal surfaces are sterilized for use intra-operatively and as animplant. As disclosed above, the sterilization process can use asterilization gas to sterilize all exposed regions of insert 100.

Insert 100 is assembled having the support structure 102 and the supportstructure 104. The support structures 102 and 104 houses electroniccircuitry 618 and respectively having the articular surface 106 and theload-bearing surface 108. The support structures 102 and 104 cancomprise in part a material such as polycarbonate, ultra high molecularweight polyethylene, metal, or other polymer materials. In the example,support structures 102 and 104 are molded polycarbonate structures.Sensors 602 are within insert 100 for measuring load magnitude andposition of load on the articular surface 106. The electronic circuitry618 is operatively coupled to sensors 602. A power source 616 within theinsert 100 powers the electronic circuitry 618 during a measurementprocess. Support structures 102 and 104 respectively have peripheralsurfaces 406 and 110 that are coupled together to form a sealedenclosure. The peripherals surfaces are sealed by adhesive, welding,elastic gasket, or other methods/devices for isolating the cavity 606from allowing any solids, liquids, or gases from entering to theexternal environment after insert 100 is assembled. In particular,cavity 606 is sealed such that any chemicals or biological matter cannotpass to the external environment. As mentioned previously, insert 100 issubjected to a sterilization process that ensures sterility of thedevice for intra-operative and implant use. Insert 100 is placed in asterile container or packaging until used in an operating room. Theinsert 100 used intra-operatively can be a disposable device that isdisposed of as a biological hazardous material after the surgicalprocedure is completed. Power source 616 powers the device for a singleuse. The sealing process uses a strong adhesive to seal supportstructures 102 and 104 to prevent the insert 100 from being used asecond time after disposal. Attempting to separate support structures102 is likely a destructive process to insert 100 thereby acting as adeterrent for unauthorized reuse.

A method of providing intra-operative muscular-skeletal parametermeasurement is supported by the embodiment disclosed hereinabove. Insert100 has the articular surface 106 that interfaces with a natural orprosthetic surface coupled to the muscular-skeletal system for allowingmovement of two bones in relation to one another. Sensors 602 withininsert 100 couple to and measure the muscular-skeletal parameter wheninstalled. The steps disclosed herein can be performed in any order orcombination. In a first step, electronic circuitry 618 is housed withinthe insert 100. Insert 100 is a self-contained measurement system havingelectronic circuitry 618, sensors 602, and a power source 616 within acavity 606. In a second step, cavity 606 is sealed and isolated from anexternal environment. In a third step, a sterilization processsterilizes the exposed or external surfaces of insert 100. Assembly ofinsert 100 occurs before the sterilization process. For example, onesterilization process comprises insert 100 being exposed to asterilization gas for a predetermined time period. In the method, thecavity 606 is not sterilized during the sterilization process. Sterilityis maintained by sealing the cavity 606 during assembly such thatsolids, liquids, or gases cannot pass through the seal. Thesterilization gas does not penetrate within cavity 606. In general, thecomponents and assembly process are tightly controlled to minimize oreliminate contaminants in cavity 606.

In a fourth step, the insert 100 is placed in a sterile container orsterile packaging after the sterilization process. The packagingmaintains the sterility of the external or exposed surfaces of insert100 until it is used as an intra-operative prosthetic component or as animplanted prosthetic component. In a fifth step, the sterile packagingis opened in a sterile environment prior to use. In one embodiment, thesterile packaging is opened within the sterile field of the operatingroom thereby minimizing a possibility of contamination of insert 100. Ina sixth step, the insert 100 is inserted into a joint of themuscular-skeletal system. The insert 100 allows a natural range ofmotion of the joint such that the bones of the joint move in relation toone another. In a seventh step, insert 100 measures one or moreparameters of the muscular-skeletal system. The measurements can occurover the range of motion and provide real-time data as adjustments aremade to the joint. In an eighth step, the insert 100 is disposed ofafter surgery. The insert 100 is a disposable item for use in a singleapplication. Typically, insert 100 is disposed of as hazardous waste dueto contact with biological matter.

In one embodiment, the enclosure of insert 100 for measuring a parameterof the muscular-skeletal system comprises a polymer material. In oneembodiment, at least one of the load-bearing surfaces of insert 100comprises polycarbonate. Polycarbonate is a lightweight material that isbiocompatible having sufficient structural strength to support jointloading. In particular, polycarbonate is used in insert 100 forintra-operative measurements to aid in the installation of a permanentor final joint prosthetic system. The use of polycarbonate provides thefurther benefit of being easily formed in complex shapes, low cost fordisposable applications, sterilizable, and transmissive to radiofrequency signals for short distance communications required forproviding real-time intra-operative quantitative data.

Referring to FIGS. 7 and 8, insert 100 comprises the support structure102 having the articular surface 106 and the support structure 104having the load bearing surface 108. The support structures 102 and 104have alignment features that align the housing together during assembly.Peripheral surfaces 110 and 406 interface or mate together when alignedand structures 102 and 104 are coupled together to form. The peripheralsurfaces 110 and 406 are sealed together such that the cavity 606encloses the self-contained measurement system for measuring a parameterof the muscular-skeletal system. The peripheral surfaces 110 and 106 aresealed by adhesive, welding, elastic seal, or other method to isolatethe cavity 606 and the measurement system from the external environment.In one embodiment, the insert 100 measures load and position of load.The cavity 606 houses, electronic circuitry 618, load sensors 602, and apower source 616. Support structures 102 and 104 can include shims tochange the height during the surgery. The insert 100 including themeasurement system is substantially dimensionally equal to the finalinsert placed in the joint.

In one embodiment, the support structures 102 and 104 are formed ofpolycarbonate. Support structures 102 and 104 can be molded forrepeatable construction and low cost. The molding process can includeinjection molding, thermoforming, vacuum forming, and mold processes.The support structures can also be machined from a solid block ofmaterial. In one embodiment, the articular surface 106 is flexible underloading by the joint during an installation process. The polycarbonatelayer comprising articular surface 106 can be made thin to allow flexingas disclosed above. A peripheral groove can also be cut in supportstructure 102 to allow a thicker polycarbonate layer comprisingarticular surface 106 to flex under loading. The thicker polycarbonatelayer comprising load-bearing surface 108 is rigid and does not flexwhereby the peripheral groove allows flexing. In one embodiment,alignment features 114 and 410 are formed in structures 102 and 104 ofpolycarbonate during the mold process. The support structure 104 furtherincludes pad regions 608 at predetermined locations comprisingpolycarbonate for supporting sensors 602. The position of pad regions608 corresponds to locations on articular surface 106. The positions areused in the calculations to identify where the load magnitude and theposition where the load is applied to the articular surface 106. Forbrevity, it should be noted that insert 100 comprising supportstructures 102 and 104 can similarly be formed of ultra-high molecularweight polyethylene as disclosed hereinabove.

FIG. 15 illustrates a cross-sectional view of planar interconnect 604coupling to sensors 602 in accordance with an example embodiment.Sensors 602 are located at each vertex of a triangular area of supportstructure 104. Sensors 602 are supported by pad regions 608 coupled tothe load-bearing surface 108. Electronic circuitry 618 at leastpartially underlies planar interconnect 604 in cavity 606 of supportstructure 104. Planar interconnect 604 is aligned to support structure104 and more specifically to sensors 602 by alignment features 114. Theplanar interconnect 604 aligns such that terminals on sensors 602 coupleto interconnect on planar interconnect 604. In the example, the sensors602 are film sensors such as piezo-resistive film sensors havingelectrical contact regions that correspond to electrical contact regionson planar interconnect 604. The planar interconnect 602 can bephysically and electrically coupled to sensors 602 by solder orconductive epoxy. In one embodiment, a spacing exists between planarinterconnect 604 and the electronic components 618. The space ensuresthat planar interconnect 604 does not contact electronic components 618when a loading is applied to insert 100.

In the illustration, electronic circuitry 618 is mounted on a printedcircuit board 622. The printed circuit board 622 can further include anintegrated antenna, power source 616, and connector 620. The planarinterconnect 604 has a flexible tab 610 that extends to and is alignedwith connector 620. In the example, flexible tab 610 has multipleconnection points that couple to connection points on connector 620. Inone embodiment, the flexible tab 610 is inserted in connector 620 and aclamp of connector 620 retains the flexible tab 610 and applies pressureto each connection to ensure a reliable electrical connection. The powersource 616, electronic circuitry 618 and sensors 602 are coupled byprinted circuit board 622 and planar interconnect 604 to form theself-contained measurement system. In an alternate embodiment, planarinterconnect 604 can couple to one or more electronic components. Forexample, planar interconnect 604 can have connection points for couplingto the power source 616 or other connection points that underlie planarinterconnect 604.

The load plate 112 is illustrated overlying planar interconnect 604. Theload plate 112 is aligned by alignment features 114 of support structure104 to sensors 602. The load plate includes openings that receivealignment features 114 therethrough. A portion of load plate 112overlies each sensor 602. In particular, load plate 112 is triangular inshape and each vertex of load plate 112 overlies a corresponding sensor602. The load plate 112 distributes a force, pressure, or load appliedto articular surface 106 of support structure 102 to sensors 602. In theembodiment, the load plate is triangular in shape.

FIG. 16 illustrates a cross-sectional view of a sensor assembly inaccordance with an example embodiment. The sensor assembly comprises thepad region 608, planar interconnect 604, sensor 602, and load plate 112.In one embodiment, sensor 602 is located on pad region 608. The sensor602 can be positioned and retained by one or more retaining features. Aportion of planar interconnect 604 is placed on sensor 602 such thatelectrical connection points between sensor 602 and planar 604interface. Planar interconnect 604 comprises a non-compressible materialthat transfers a force, pressure, or load to sensor 602. The load plate112 is placed on planar interconnect 604 to couple the force, pressure,or load to sensor 602. The load plate 112 comprises a rigid material ormetal. In one embodiment, load plate 112 is formed from steel. The loadplate 112 has a surface that is co-planar to a surface of planarinterconnect 604. The sensing assembly can be assembled by a process ofstacking components.

FIG. 17 illustrates a cross-sectional view of assembled insert 100 inaccordance with an example embodiment. Insert 100 comprises supportstructure 102 coupled to support structure 104 whereby the interior ofthe self-contained measurement system is isolated from the externalenvironment. Support structures 102 and 104 respectively have thearticular surface 106 and load-bearing surface 108 for coupling to shim118 or one or more joint prosthetic components. A shim 118 can be usedto change height and couple to a prosthetic component. Insert 100inserted in the joint allows articulation of one bone in relation toanother bone.

Insert 100 measures a parameter of the muscular-skeletal system. In oneembodiment, three sensors measure a force, pressure, or load magnitudeapplied to the articular surface 106 when the insert 100 is insertedbetween other installed prosthetic components. Each sensor couples to apredetermined area of articular surface 106. The load-bearing surface108 supports each sensor. Measurement of the load magnitude applied toarticular surface 106 and position of load on articular surface 106 canbe calculated from the sensor measurements.

Alignment features 114 are shown extending from support structure 104.Alignment features 114 couple through openings in planar interconnect604, load plate 112, and into openings 408 of support structure 102.Alignment features 114 align interconnect 604 and load plate 112 tosupport structure 104 and more particularly to pad regions 608 andsensors 602. Planar interconnect 604 overlies and electrically couplesto terminals of sensors 602. Planar interconnect 604 couples the threesensors 602 to electronic circuitry 618. Load plate 112 can have asurface that is co-planar to the surface of planar interconnect 604. Asmentioned previously, load plate 112 may be triangular in shape and issupported at each vertex by sensors 602 and pad regions 608. Electroniccircuitry 618 is shown in the cavity underlying the planar interconnect604 and load plate 112. The planar interconnect 604 is spaced fromelectronic circuitry 618 to prevent contact under all loadingconditions. In general, piezo-resistive film sensors used as sensors 602to measure force, pressure, or load do not compress significantly overthe expected load range for intra-operative installation measurements.

The support structure 102 includes interior surface 404 that couples toload plate 112. Interior surface 404 of support structure 102 isco-planar to the surface of the load plate 112. In one embodiment,support structure 102 can be formed, molded, or machined from a polymermaterial such as polycarbonate or ultra high molecular weightpolyethylene having articular surface 106 and interior surface 404. Thelayer of polymer material between articular surface 106 and interiorsurface 404 of support structure 102 can flex but does not compresssubstantially under loading. Interior surface 404 of support structure102 has openings 408 for receiving alignment features 114. Alignmentfeatures 114 align support structure 104 to support structure 102.Peripheral regions 110 and 406 respectively of support structure 104 andsupport structure 102 are coupled to seal or isolate the measurementsystem from the external environment. Welding or an adhesive can be usedto form the seal between peripheral regions 110 and 406.

A method of assembling a self-contained measurement system within aprosthetic component is supported by the embodiment disclosedhereinabove. In general, the assembly method provides a highperformance, small form factor, reliable, and sterile measurement systemsuitable for prosthetic components, tools, and equipment. In a firststep, the electronic circuitry 618 is inserted into the cavity 606 ofsupport structure 104. The electronic circuitry 618 can be mounted on aprinted circuit board 622. Printed circuit board 622 can be supportedand retained by one or more features formed in support structure 104.Pad regions 608 are at the vertices of a triangle. Pad regions 608 aresupported by and couple to load-bearing surface 108. In a second step,sensors 602 are placed on the pad regions 608 of support structure 104.The pad regions 608 can have alignment and retaining features forholding sensors 602 in a predetermined position. In one embodiment, thesensors 602 are piezo-resistive film sensors having a low profile. Inthe example, a portion of sensors 602 can extend over the electroniccircuitry 618 but do not make physical contact thereto. In a third step,an interconnect 604 is aligned to sensors 602 by alignment features 114.The alignment features 114 are formed in support structure 104. Inparticular, alignment features 114 couple through slots or openings ininterconnect 604. In one embodiment, interconnect 604 is planar andpartially overlies sensors 602 and cavity 606. The planar shape ofinterconnect 604 overlies but does not physically contact electroniccircuitry 618. Interconnect 604 has conductive regions that align withand couple to corresponding conductive regions on sensors 602. In afourth step, interconnect 604 can be coupled by solder, conductiveepoxy, a compressive force, and other known methods to make appropriateelectrical connection to the terminals of sensors 602.

The printed circuit board 622 can include a connector. The connector canhave multiple connection points and a retention mechanism. The connectorcouples to electronic circuitry 618 of the measurement system. Theinterconnect 604 can include a tab that extends from interconnect 604.The tab is flexible. In a fifth step, the tab is inserted into theconnector. The connector can have a clamping mechanism or otherretaining device to hold the connection points on the tab ofinterconnect 604 coupled with connection points on the connector. Theclamping mechanism forcibly retains the tab in the connector to preventdecoupling and maintain electrical contact during use. In a seventhstep, load plate 112 couples to alignment features 114 of supportstructure 104. The alignment features 114 align the load plate 112 tothe sensors 602. In an eighth step, the load plate 112 overlies sensors602. Under loading, the load plate 112 couples and distributes a force,pressure, or load to each sensor corresponding to the location of anapplied force, pressure, or load to the articular surface 106. In aninth step, the support structure 102 having the articular surface 106is aligned to the support structure 104. In the example, alignment isachieved by alignment features 114 coupling to alignment features 410 insupport structure 102. In the example, alignment features 410 areopenings in the interior surface of support structure 102. Supportstructures 102 and 104 are coupled together such that the interiorsurface of support structure 102 couples to load plate 112. Supportstructures 102 and 104 are sealed together thereby forming an enclosuresurrounding electronic circuitry 618 and sensors 602 that is isolatedfrom the external environment.

FIG. 18 illustrates a block diagram of the components of an insert 1800in accordance with an example embodiment. It should be noted that insert1800 could comprise more or less than the number of components shown. Inone embodiment, insert 1800 is a prosthetic component allowing parametermeasurement and articulation of the muscular-skeletal system. Asillustrated, the insert 1800 includes one or more sensors 1802, padregions 1804, a load plate 1806, a power source 1808, electroniccircuitry 1810, a transceiver 1812, and an accelerometer 1814. In anon-limiting example, the insert 1800 can measure an applied compressiveforce.

The sensors 1802 can be positioned, engaged, attached, or affixed to thecontact surfaces 1816 and 1818. In at least one example embodiment,contact surfaces 1816 and 1818 are load-bearing surfaces. In the exampleof a knee insert, surface 1816 is a load-bearing articular surface thatcontacts a natural or prosthetic femoral condyle to allow movement of aknee joint. Contact surface 1818 is a load-bearing surface. In theexample, contact surface 1818 contacts a tibial surface or a tibialprosthetic component in a fixed position. Surfaces 1816 and 1818 canmove and tilt with changes in applied load actions, which can betransferred to the sensors 1802 and measured by the electronic circuitry1810. The electronic circuitry 1810 measures physical changes in thesensors 1802 to determine parameters of interest, for example a level,distribution and direction of forces acting on the contact surfaces 1816and 1818. The insert 1800 is powered by an internal power source 1808.

The architecture allows different types of sensors to be used to measurea force, pressure, or load. Sensor types such as piezo-resistivesensors, mems devices, strain gauges, and mechanical sensors can overliepad regions 1804 to generate signals related to a compressive forceapplied to surface 1816. As one example, sensors 1802 can comprise anelastic or compressible propagation structure between a first transducerand a second transducer. The transducers can be an ultrasound (orultrasonic) resonator while the elastic or compressible propagationstructure acts as an ultrasound waveguide. The electronic circuitry 1810is electrically coupled to the transducers to translate changes in thelength (or compression or extension) of the compressible propagationstructure to parameters of interest, such as force. The system measuresa change in the length of the compressible propagation structure (e.g.,waveguide) responsive to an applied force and converts this change intoelectrical signals, which can be transmitted via the transceiver 1812 toconvey a level, direction, or location of the applied force. Forexample, the compressible propagation structure has known and repeatablecharacteristics of the applied force versus the length of the waveguide.Precise measurement of the length of the waveguide using ultrasonicsignals can be converted to a force using the known characteristics. Inyet other arrangements, the sensors can include piezoelectric, pH,motion, capacitive, optical or temperature sensors to provide otherparameter measurements of the muscular-skeletal system.

In one embodiment, electronic circuitry 1810 comprises an applicationspecific integrated circuit (ASIC). The architecture of the ASICsupports performance, power consumption, and form factor specificationsrequired for a self contained intra-operative and implant measurementprosthetic component. In particular, electronic circuitry 1810 includesmultiple inputs, outputs, and input/outputs thereby allowing both serialand parallel measurement and data transfer. The ASIC also incorporatesdigital control logic to manage control functions of insert 1800. Theelectronic circuitry 1810 or ASIC incorporates A/D and D/A circuitry(not shown) to digitize current and voltage output from different typesof sensing components.

The accelerometer 1814 can measure acceleration and static gravitationalpull. Accelerometer 1814 can be single-axis and multi-axis accelerometerstructures that detect magnitude and direction of the acceleration as avector quantity. Accelerometer 1814 can also be used to senseorientation, vibration, impact and shock. The electronic circuitry 1810in conjunction with the accelerometer 1814 and sensors 1802 can measureparameters of interest (e.g., distributions of load, force, pressure,displacement, movement, rotation, torque and acceleration) relative toorientations of insert 1800 with respect to a reference point. In suchan arrangement, spatial distributions of the measured parametersrelative to a chosen frame of reference can be computed and presentedfor real-time display.

The transceiver 1812 comprises a transmitter 1822 and an antenna 1820 topermit wireless operation and telemetry functions. In variousembodiments, the antenna 1820 can be configured by design as anintegrated loop antenna. The integrated loop antenna is configured atvarious layers and locations on a printed circuit board having otherintercoupled electrical components. Once initiated the transceiver 1812can broadcast the parameters of interest in real-time. The telemetrydata can be received and decoded with various receivers, or with acustom receiver. The wireless operation can eliminate distortion of, orlimitations on, measurements caused by the potential for physicalinterference by, or limitations imposed by, wiring and cables couplingthe sensing module with a power source or with associated datacollection, storage, display equipment, and data processing equipment.

The transceiver 1812 receives power from the power source 1808 and canoperate at low power over various radio frequencies by way of efficientpower management schemes, for example, incorporated within theelectronic circuitry 1810. As one example, the transceiver 1812 cantransmit data at selected frequencies in a chosen mode of emission byway of the antenna 1820. The selected frequencies can include, but arenot limited to, ISM bands recognized in International TelecommunicationUnion regions 1, 2 and 3. A chosen mode of emission can be, but is notlimited to, Gaussian Frequency Shift Keying, (GFSK), Amplitude ShiftKeying (ASK), Phase Shift Keying (PSK), Minimum Shift Keying (MSK),Frequency Modulation (FM), Amplitude Modulation (AM), or other versionsof frequency or amplitude modulation (e.g., binary, coherent,quadrature, etc.).

The antenna 1820 can be integrated with components of the sensing moduleto provide the radio frequency transmission. The antenna 1820 andcoupling of electronic circuitry 1810 can be integrated into a printedcircuit board. The antenna 1820 can further include a matching networkfor efficient transfer of the signal. This level of integration of theantenna and electronics enables reductions in the size and cost ofwireless equipment. Potential applications may include, but are notlimited to any type of short-range handheld, wearable, or other portablecommunication equipment where compact antennas are commonly used. Thisincludes disposable modules or devices as well as reusable modules ordevices and modules or devices for long-term use.

The power source 1808 provides power to electronic components of theinsert 1800. In one embodiment, the power source 1808 can be charged bywired energy transfer, short-distance wireless energy transfer or acombination thereof. External power sources for providing wirelessenergy to power source 1808 can include, but are not limited to, abattery or batteries, an alternating current power supply, a radiofrequency receiver, an electromagnetic induction coil, energyharvesting, magnetic resonance a photoelectric cell or cells, athermocouple or thermocouples, or an ultrasound transducer ortransducers. By way of power source 1808, insert 1800 can be operatedwith a single charge until the internal energy is drained. It can berecharged periodically to enable continuous operation. The power source1808 can further utilize power management techniques for efficientlysupplying and providing energy to the components of insert 1800 tofacilitate measurement and wireless operation. Power managementcircuitry can be incorporated on the ASIC to manage both the ASIC powerconsumption as well as other components of the system.

The power source 1808 minimizes additional sources of energy radiationrequired to power the sensing module during measurement operations. Inone embodiment, as illustrated, the energy storage 1808 can include acapacitive energy storage device 1824 and an induction coil 1826. Theexternal source of charging power can be coupled wirelessly to thecapacitive energy storage device 1824 through the electromagneticinduction coil or coils 1826 by way of inductive charging. The chargingoperation can be controlled by power management systems designed into,or with, the electronic circuitry 1810. For example, during operation ofelectronic circuitry 1810, power can be transferred from capacitiveenergy storage device 1810 by way of efficient step-up and step-downvoltage conversion circuitry. This conserves operating power of circuitblocks at a minimum voltage level to support the required level ofperformance. An alternative to the capacitive energy storage device 1824is a rechargeable battery disclosed hereinabove that could be rechargedwirelessly as described herein.

In one configuration, the external power source can further serve tocommunicate downlink data to the transceiver 1812 during a rechargingoperation. For instance, downlink control data can be modulated onto thewireless energy source signal and thereafter demodulated from theinduction coil 1826 by way of electronic circuitry 1810. This can serveas a more efficient way for receiving downlink data instead ofconfiguring the transceiver 1812 for both uplink and downlink operation.As one example, downlink data can include updated control parametersthat the insert 1800 uses when making a measurement, such as externalpositional information, or for recalibration purposes. It can also beused to download a serial number or other identification data.

The electronic circuitry 1810 manages and controls various operations ofthe components of the sensing module, such as sensing, power management,telemetry, and acceleration sensing. It can include analog circuits,digital circuits, integrated circuits, discrete components, or anycombination thereof. In one arrangement, it can be partitioned amongintegrated circuits and discrete components to minimize powerconsumption without compromising performance. Partitioning functionsbetween digital and analog circuit enhances design flexibility andfacilitates minimizing power consumption without sacrificingfunctionality or performance. Accordingly, the electronic circuitry 1810can comprise one or more integrated circuits or ASICs, for example,specific to a core signal-processing algorithm.

In another arrangement, the electronic circuitry 1810 can comprise acontroller such as a programmable processor, a Digital Signal Processor(DSP), a microcontroller, or a microprocessor, with associated storagememory and logic. The controller can utilize computing technologies withassociated storage memory such a Flash, ROM, RAM, SRAM, DRAM or otherlike technologies for controlling operations of the aforementionedcomponents of the sensing module. In one arrangement, the storage memorymay store one or more sets of instructions (e.g., software) embodyingany one or more of the methodologies or functions described herein. Theinstructions may also reside, completely or at least partially, withinother memory, and/or a processor during execution thereof by anotherprocessor or computer system.

The electronics assemblage also supports testability and calibrationfeatures that assure the quality, accuracy, and reliability of thecompleted wireless sensing module or device. A temporary bi-directionalinterconnect assures a high level of electrical observability andcontrollability of the electronics. The test interconnect also providesa high level of electrical observability of the sensing subsystem,including the transducers, waveguides, and mechanical spring or elasticassembly. Carriers or fixtures emulate the final enclosure of thecompleted wireless sensing module or device during manufacturingprocessing thus enabling capture of accurate calibration data for thecalibrated parameters of the finished wireless sensing module or device.These calibration parameters are stored within the on-board memoryintegrated into the electronics assemblage.

Applications for the electronic assembly comprising the sensors 1802 andelectronic circuitry 1810 may include, but are not limited to,disposable modules or devices as well as reusable modules or devices andmodules or devices for long-term use. In addition to non-medicalapplications, examples of a wide range of potential medical applicationsmay include, but are not limited to, implantable devices, modules withinimplantable devices, intra-operative implants or modules withinintra-operative implants or trial inserts, modules within inserted oringested devices, modules within wearable devices, modules withinhandheld devices, modules within instruments, appliances, equipment, oraccessories of all of these, or disposables within implants, trialinserts, inserted or ingested devices, wearable devices, handhelddevices, instruments, appliances, equipment, or accessories to thesedevices, instruments, appliances, or equipment.

FIG. 19 illustrates a communications system 1900 for short-rangetelemetry in accordance with an example embodiment. As illustrated, thecommunications system 1900 comprises medical device communicationscomponents 1910 in a prosthetic component and receiving systemcommunications in a processor based system. In one embodiment, thereceiving system communications are in or coupled to a computer orlaptop computer that is external to the sterile field of the operatingroom. The surgeon can view the laptop screen or a display coupled to thecomputer while performing surgery. The medical device communicationscomponents 1910 are operatively coupled to include, but not limited to,the antenna 1912, a matching network 1914, the telemetry transceiver1916, a CRC circuit 1918, a data packetizer 1922, a data input 1924, apower source 1926, and an application specific integrated circuit (ASIC)1920. The medical device communications components 1910 may include moreor less than the number of components shown and are not limited to thoseshown or the order of the components.

The receiving station communications components comprise an antenna1952, a matching network 1954, the telemetry transceiver 1956, the CRCcircuit 1958, the data packetizer 1960, and optionally a USB interface1962. Notably, other interface systems can be directly coupled to thedata packetizer 1960 for processing and rendering sensor data.

In general, the electronic circuitry is operatively coupled to one ormore sensors of the prosthetic component. In one embodiment, the datagenerated by the one or more sensors can comprise a voltage or currentvalue from a mems structure, piezo-resistive sensor, strain gauge,mechanical sensor or other sensor type that is used to measure aparameter of the muscular-skeletal system. The data packetizer 1922assembles the sensor data into packets; this includes sensor informationreceived or processed by ASIC 1920. The ASIC 1920 can comprise specificmodules for efficiently performing core signal processing functions ofthe medical device communications components 1910. The ASIC 1920provides the further benefit of reducing the form factor of insertsensing device to meet dimensional requirements for integration intotemporary or permanent prosthetic components.

The CRC circuit 1918 applies error code detection on the packet data.The cyclic redundancy check is based on an algorithm that computes achecksum for a data stream or packet of any length. These checksums canbe used to detect interference or accidental alteration of data duringtransmission. Cyclic redundancy checks are especially good at detectingerrors caused by electrical noise and therefore enable robust protectionagainst improper processing of corrupted data in environments havinghigh levels of electromagnetic activity. The telemetry transceiver 1916then transmits the CRC encoded data packet through the matching network1914 by way of the antenna 1912. The matching networks 1914 and 1954provide an impedance match for achieving optimal communication powerefficiency.

The receiving system communications components 1950 receive transmissionsent by medical device communications components 1910. In oneembodiment, telemetry transceiver 1916 is operated in conjunction with adedicated telemetry transceiver 1956 that is constrained to receive adata stream broadcast on the specified frequencies in the specified modeof emission. The telemetry transceiver 1956 by way of the receivingstation antenna 1952 detects incoming transmissions at the specifiedfrequencies. The antenna 1952 can be a directional antenna that isdirected to a directional antenna of components 1910. Using at least onedirectional antenna can reduce data corruption while increasing datasecurity by further limiting where the data is radiated. A matchingnetwork 1954 couples to antenna 1952 to provide an impedance match thatefficiently transfers the signal from antenna 1952 to telemetry receiver1956. Telemetry receiver 1956 can reduce a carrier frequency in one ormore steps and strip off the information or data sent by components1910. Telemetry receiver 1956 couples to CRC circuit 1958. CRC circuit1958 verifies the cyclic redundancy checksum for individual packets ofdata. CRC circuit 1958 is coupled to data packetizer 1960. Datapacketizer 1960 processes the individual packets of data. In general,the data that is verified by the CRC circuit 1958 is decoded (e.g.,unpacked) and forwarded to an external data processing device, such asan external computer, for subsequent processing, display, or storage orsome combination of these.

The telemetry transceiver 1956 is designed and constructed to operate onvery low power such as, but not limited to, the power available from thepowered USB port 1962, or a battery. In another embodiment, thetelemetry transceiver 1956 is designed for use with a minimum ofcontrollable functions to limit opportunities for inadvertent corruptionor malicious tampering with received data. The telemetry transceiver1956 can be designed and constructed to be compact, inexpensive, andeasily manufactured with standard manufacturing processes while assuringconsistently high levels of quality and reliability.

In one configuration, the communication system 1900 operates in atransmit-only operation with a broadcasting range on the order of a fewmeters to provide high security and protection against any form ofunauthorized or accidental query. The transmission range can becontrolled by the transmitted signal strength, antenna selection, or acombination of both. A high repetition rate of transmission can be usedin conjunction with the Cyclic Redundancy Check (CRC) bits embedded inthe transmitted packets of data during data capture operations therebyenabling the receiving system to discard corrupted data withoutmaterially affecting display of data or integrity of visualrepresentation of data, including but not limited to measurements ofload, force, pressure, displacement, flexion, attitude, and positionwithin operating or static physical systems.

By limiting the operating range to distances on the order of a fewmeters, the telemetry transceiver 1916 can be operated at very low powerin the appropriate emission mode or modes for the chosen operatingfrequencies without compromising the repetition rate of the transmissionof data. This mode of operation also supports operation with compactantennas, such as an integrated loop antenna. The combination of lowpower and compact antennas enables the construction of, but is notlimited to, highly compact telemetry transmitters that can be used for awide range of non-medical and medical applications.

The transmitter security as well as integrity of the transmitted data isassured by operating the telemetry system within predeterminedconditions. The security of the transmitter cannot be compromisedbecause it is operated in a transmit-only mode and there is no pathwayto hack into medical device communications components. The integrity ofthe data is assured with the use of the CRC algorithm and the repetitionrate of the measurements. The limited broadcast range of the deviceminimizes the risk of unauthorized reception of the data. Even ifunauthorized reception of the data packets should occur, there arecounter measures in place that further mitigate data access. A firstmeasure is that the transmitted data packets contain only binary bitsfrom a counter along with the CRC bits. A second measure is that no datais available or required to interpret the significance of the binaryvalue broadcast at any time. A third measure that can be implemented isthat no patient or device identification data is broadcast at any time.

The telemetry transceiver 1916 can also operate in accordance with someFCC regulations. According to section 18.301 of the FCC regulations theISM bands within the USA include 6.78, 13.56, 27.12, 30.68, 915, 2450,and 5800 MHz as well as 24.125, 61.25, 122.50, and 245 GHz. Globallyother ISM bands, including 433 MHz, are defined by the InternationalTelecommunications Union in some geographic locations. The list ofprohibited frequency bands defined in 18.303 are “the following safety,search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194kHz, 8354-8374 kHz, 121.4-121.6 MHz, 156.7-156.9 MHz, and 242.8-243.2MHz.” Section 18.305 stipulates the field strength and emission levelsISM equipment must not exceed when operated outside defined ISM bands.In summary, it may be concluded that ISM equipment may be operatedworldwide within ISM bands as well as within most other frequency bandsabove 9 KHz given that the limits on field strengths and emission levelsspecified in section 18.305 are maintained by design or by activecontrol. As an alternative, commercially available ISM transceivers,including commercially available integrated circuit ISM transceivers,may be designed to fulfill these field strengths and emission levelrequirements when used properly.

In one configuration, the telemetry transceiver 1916 can also operate inunlicensed ISM bands or in unlicensed operation of low power equipment,wherein the ISM equipment (e.g., telemetry transmitter 1916) may beoperated on ANY frequency above 9 kHz except as indicated in Section18.303 of the FCC code.

Wireless operation eliminates distortion of, or limitations on,measurements caused by the potential for physical interference by, orlimitations imposed by, wiring and cables coupling the wireless sensingmodule or device with a power source or with data collection, storage,or display equipment. Power for the sensing components and electroniccircuits is maintained within the wireless sensing module or device onan internal energy storage device. This energy storage device is chargedwith external power sources including, but not limited to, a battery orbatteries, super capacitors, capacitors, an alternating current powersupply, a radio frequency receiver, an electromagnetic induction coil, aphotoelectric cell or cells, a thermocouple or thermocouples, or anultrasound transducer or transducers. The wireless sensing module may beoperated with a single charge until the internal energy source isdrained or the energy source may be recharged periodically to enablecontinuous operation. The embedded power supply minimizes additionalsources of energy radiation required to power the wireless sensingmodule or device during measurement operations. Telemetry functions arealso integrated within the wireless sensing module or device. Onceinitiated the telemetry transmitter continuously broadcasts measurementdata in real time. Telemetry data may be received and decoded withcommercial receivers or with a simple, low cost custom receiver.

FIG. 20 illustrates a communication network 2000 for measurement andreporting in accordance with an example embodiment. Briefly,communication network 2000 expands broad data connectivity to otherdevices or services. As illustrated, the measurement and reportingsystem 2055 can be communicatively coupled to the communications network2000 and any associated systems or services.

As one example, the measurement system 2055 can share its parameters ofinterest (e.g., angles, load, balance, distance, alignment,displacement, movement, rotation, and acceleration) with remote servicesor providers, for instance, to analyze or report on surgical status oroutcome. This data can be shared for example with a service provider tomonitor progress or with plan administrators for surgical monitoringpurposes or efficacy studies. The communication network 2000 can furtherbe tied to an Electronic Medical Records (EMR) system to implementhealth information technology practices. In other embodiments, thecommunication network 2000 can be communicatively coupled to HISHospital Information System, HIT Hospital Information Technology and HIMHospital Information Management, EHR Electronic Health Record, CPOEComputerized Physician Order Entry, and CDSS Computerized DecisionSupport Systems. This provides the ability of different informationtechnology systems and software applications to communicate, to exchangedata accurately, effectively, and consistently, and to use the exchangeddata.

The communications network 2000 can provide wired or wirelessconnectivity over a Local Area Network (LAN) 2001, a Wireless Local AreaNetwork (WLAN) 2005, a Cellular Network 2014, and/or other radiofrequency (RF) system. The LAN 2001 and WLAN 2005 can be communicativelycoupled to the Internet 2020, for example, through a central office. Thecentral office can house common network switching equipment fordistributing telecommunication services. Telecommunication services caninclude traditional POTS (Plain Old Telephone Service) and broadbandservices such as cable, HDTV, DSL, VoIP (Voice over Internet Protocol),IPTV (Internet Protocol Television), Internet services, and so on.

The communication network 2000 can utilize common computing andcommunications technologies to support circuit-switched and/orpacket-switched communications. Each of the standards for Internet 2020and other packet switched network transmission (e.g., TCP/IP, UDP/IP,HTML, HTTP, RTP, MMS, SMS) represent examples of the state of the art.Such standards are periodically superseded by faster or more efficientequivalents having essentially the same functions. Accordingly,replacement standards and protocols having the same functions areconsidered equivalent.

The cellular network 2014 can support voice and data services over anumber of access technologies such as GSM-GPRS, EDGE, CDMA, UMTS, WiMAX,2G, 3G, 4G, WAP, software defined radio (SDR), and other knowntechnologies. The cellular network 2014 can be coupled to base receiver2010 under a frequency-reuse plan for communicating with mobile devices2002.

The base receiver 2010, in turn, can connect the mobile device 2002 tothe Internet 2020 over a packet switched link. Internet 2020 can supportapplication services and service layers for distributing data from themeasurement system 2055 to the mobile device 2002. The mobile device2002 can also connect to other communication devices through theInternet 2020 using a wireless communication channel.

The mobile device 2002 can also connect to the Internet 2020 over theWLAN 2005. Wireless Local Access Networks (WLANs) provide wirelessaccess within a local geographical area. WLANs are typically composed ofa cluster of Access Points (APs) 2004 also known as base stations. Themeasurement system 2055 can communicate with other WLAN stations such aslaptop 2003 within the base station area. In typical WLANimplementations, the physical layer uses a variety of technologies suchas 802.11b or 802.11g WLAN technologies. The physical layer may useinfrared, frequency hopping spread spectrum in the 2.4 GHz Band, directsequence spread spectrum in the 2.4 GHz Band, or other accesstechnologies, for example, in the 5.8 GHz ISM band or higher ISM bands(e.g., 24 GHz, etc).

By way of the communication network 2000, the measurement system 2055can establish connections with a remote server 2030 on the network andwith other mobile devices for exchanging data. The remote server 2030can have access to a database 2040 that is stored locally or remotelyand which can contain application specific data. The remote server 2030can also host application services directly, or over the internet 2020.

It should be noted that very little data exists on implanted orthopedicdevices. Most of the data is empirically obtained by analyzingorthopedic devices that have been used in a human subject or simulateduse. Wear patterns, material issues, and failure mechanisms are studied.Although information can be garnered through this type of empiricalstudy, it does not yield substantive data about the initialinstallation, post-operative use, and long-term use from a measurementperspective. Just as each person is different, each device installationis different having variations in initial loading, balance, andalignment. Having measured quantitative data and using the data toinstall an orthopedic device will greatly increase the consistency ofthe implant procedure thereby reducing rework and maximizing the life ofthe device. In at least one example embodiment, the measured data can becollected to a database where it can be stored and analyzed. Forexample, once a relevant sample of the measured data is collected, itcan be used to define optimal initial measured settings, geometries, andalignments for maximizing the life and usability of an implantedorthopedic device.

FIG. 21 illustrates a diagrammatic representation of a machine in theform of a computer system 2100 within which a set of instructions, whenexecuted, may cause the machine to perform any one or more of themethodologies discussed above. In some embodiments, the machine operatesas a standalone device. In some embodiments, the machine may beconnected (e.g., using a network) to other machines. In a networkeddeployment, the machine may operate in the capacity of a server or aclient user machine in server-client user network environment, or as apeer machine in a peer-to-peer (or distributed) network environment.

The machine may comprise a server computer, a client user computer, apersonal computer (PC), a tablet PC, a laptop computer, a desktopcomputer, a control system, a network router, switch or bridge, or anymachine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. It will beunderstood that a device of the present disclosure includes broadly anyelectronic device that provides voice, video or data communication.Further, while a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein.

The computer system 2100 may include a processor 2102 (e.g., a centralprocessing unit (CPU), a graphics processing unit (GPU, or both), a mainmemory 2104 and a static memory 2106, which communicate with each othervia a bus 2108. The computer system 2100 may further include a videodisplay unit 2110 (e.g., a liquid crystal display (LCD), a flat panel, asolid-state display, or a cathode ray tube (CRT)). The computer system2100 may include an input device 2112 (e.g., a keyboard), a cursorcontrol device 2114 (e.g., a mouse), a disk drive unit 2116, a signalgeneration device 2118 (e.g., a speaker or remote control) and a networkinterface device 2120.

The disk drive unit 2116 can be other types of memory such as flashmemory and may include a machine-readable medium 2122 on which is storedone or more sets of instructions (e.g., software 2124) embodying any oneor more of the methodologies or functions described herein, includingthose methods illustrated above. The instructions 2124 may also reside,completely or at least partially, within the main memory 2104, thestatic memory 2106, and/or within the processor 2102 during executionthereof by the computer system 2100. The main memory 2104 and theprocessor 2102 also may constitute machine-readable media.

Dedicated hardware implementations including, but not limited to,application specific integrated circuits, programmable logic arrays andother hardware devices can likewise be constructed to implement themethods described herein. Applications that may include the apparatusand systems of various embodiments broadly include a variety ofelectronic and computer systems. Some embodiments implement functions intwo or more specific interconnected hardware modules or devices withrelated control and data signals communicated between and through themodules, or as portions of an application-specific integrated circuit.Thus, the example system is applicable to software, firmware, andhardware implementations.

In accordance with various embodiments of the present disclosure, themethods described herein are intended for operation as software programsrunning on a computer processor. Furthermore, software implementationscan include, but not limited to, distributed processing orcomponent/object distributed processing, parallel processing, or virtualmachine processing can also be constructed to implement the methodsdescribed herein.

The present disclosure contemplates a machine readable medium containinginstructions 2124, or that which receives and executes instructions 2124from a propagated signal so that a device connected to a networkenvironment 2126 can send or receive voice, video or data, and tocommunicate over the network 2126 using the instructions 2124. Theinstructions 2124 may further be transmitted or received over a network2126 via the network interface device 2120.

While the machine-readable medium 2122 is shown in an example embodimentto be a single medium, the term “machine-readable medium” should betaken to include a single medium or multiple media (e.g., a centralizedor distributed database, and/or associated caches and servers) thatstore the one or more sets of instructions. The term “machine-readablemedium” shall also be taken to include any medium that is capable ofstoring, encoding or carrying a set of instructions for execution by themachine and that cause the machine to perform any one or more of themethodologies of the present disclosure.

The term “machine-readable medium” shall accordingly be taken toinclude, but not be limited to: solid-state memories such as a memorycard or other package that houses one or more read-only (non-volatile)memories, random access memories, or other re-writable (volatile)memories; magneto-optical or optical media such as a disk or tape; andcarrier wave signals such as a signal embodying computer instructions ina transmission medium; and/or a digital file attachment to e-mail orother self-contained information archive or set of archives isconsidered a distribution medium equivalent to a tangible storagemedium. Accordingly, the disclosure is considered to include any one ormore of a machine-readable medium or a distribution medium, as listedherein and including art-recognized equivalents and successor media, inwhich the software implementations herein are stored.

Although the present specification describes components and functionsimplemented in the embodiments with reference to particular standardsand protocols, the disclosure is not limited to such standards andprotocols. Each of the standards for Internet and other packet switchednetwork transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP) representexamples of the state of the art. Such standards are periodicallysuperseded by faster or more efficient equivalents having essentiallythe same functions. Accordingly, replacement standards and protocolshaving the same functions are considered equivalents.

The illustrations of embodiments described herein are intended toprovide a general understanding of the structure of various embodiments,and they are not intended to serve as a complete description of all theelements and features of apparatus and systems that might make use ofthe structures described herein. Many other embodiments will be apparentto those of skill in the art upon reviewing the above description. Otherembodiments may be utilized and derived therefrom, such that structuraland logical substitutions and changes may be made without departing fromthe scope of this disclosure. Figures are also merely representationaland may not be drawn to scale. Certain proportions thereof may beexaggerated, while others may be minimized. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense.

In general, artificial components for other joint replacement surgerieshave a similar operational form as the knee joint example. The jointtypically comprises two or more bones with a cartilaginous surface as anarticular surface that allows joint movement. The cartilage also acts toabsorb loading on the joint and prevents bone-to-bone contact.Reconstruction of the hip, spine, shoulder, and other joints has similarfunctioning insert structures having at least one articular surface.Like the knee joint, these other insert structures typically comprise apolymer material. The polymer material is formed for a particular jointstructure. For example, the hip insert is formed in a cup shape that isfitted into the pelvis. In general, the size and thickness of theseother joint inserts allow the integration of the sensing module. Itshould be noted that the sensing module disclosed herein contemplatesuse in both trial inserts and permanent inserts for the other joints ofthe muscular-skeletal system thereby providing quantitative parametermeasurements during and post surgery.

While the present invention has been described with reference toparticular embodiments, those skilled in the art will recognize thatmany changes may be made thereto without departing from the spirit andscope of the present invention. Each of these embodiments and obviousvariations thereof is contemplated as falling within the spirit andscope of the invention.

What is claimed is:
 1. A measurement system for measuring loadingapplied by a muscular-skeletal system comprising: an insert configuredto measure loading value and loading location, where the insertincludes: a first support structure having an articular surface and amajor interior surface, wherein the major interior surface is planar,wherein the first support structure has a first region with a firstthickness and a second region with a second thickness, and wherein thefirst and second thicknesses are different; a load plate wherein theload plate has a major planar surface, wherein the major planar surfaceof the load plate couples to the major interior surface of the firstsupport structure; at least three sensors, where the articular surfaceis configured to transfer loading to the load plate, wherein the loadplate is configured to transfer loading to the at least three sensors,wherein data from the at least three sensors is configured to be used bya processor to determine loading location and loading value on thearticular surface, wherein the first support structure includes acircumferential groove formed in a periphery of the first supportstructure, the circumferential groove allowing the articular surface toflex under loading.
 2. A measurement system for measuring loadingapplied by a muscular-skeletal system comprising: an insert configuredto measure loading value and loading location, where the insertincludes: a first support structure having an articular surface and amajor surface wherein the first support structure includes acircumferential groove formed in a periphery of the first supportstructure, the circumferential groove allowing the articular surface toflex under loading; at least three sensors underlying the articularsurface of the first support structure, wherein measurement data fromthe at least three sensors is configured to be used by a processor todetermine loading location and loading value on the articular surface; aload plate coupled between the major surface of the first supportstructure and the at least three sensors; and a second support structurecoupled to the first support structure where the first and secondsupport structures are configured to form a housing that isolates the atleast three sensors from an external environment.
 3. The measurementsystem of claim 2 further including: electronic circuitry coupled to theat least three sensors configured to receive measurement data from theat least three sensors and transmit the measurement data from theinsert; and a power source configured to provide power to the electroniccircuitry and the at least three sensors where the electronic circuitryand power source are in the housing, where the first support structurehas a first region with a first thickness and a second region with asecond thickness, and where the first and second thicknesses aredifferent.
 4. A measurement system for measuring loading applied by amuscular-skeletal system comprising: a housing configured to measure aloading value and loading location, where an insert includes: a firstsupport structure having a surface configured to couple to themuscular-skeletal system and an internal major surface wherein the firstsupport structure includes a circumferential groove formed in aperiphery of the first support structure, the circumferential grooveallowing the surface to flex under loading; at least three sensorsunderlying the internal major surface of the first support structure;electronic circuitry coupled to the at least three sensors where theelectronic circuitry is configured to receive measurement data from theat least three sensors and transmit measurement data from the at leastthree sensors; a power source configured to power the at least threesensors and the electronic circuitry; a second support structure coupledto the first support structure where the first and second structurescouple together to form a housing that encloses and isolates the atleast three sensors, power source, and electronic circuitry from anexternal environment; and a processor configured to receive measurementdata where the processor is configured to use the measurement data fromthe at least three sensors to determine loading location and loadingvalue on the surface of the first support structure.
 5. The measurementsystem of claim 4 where the first support structure comprisespolycarbonate.
 6. The measurement system of claim 4 wherein the internalmajor surface is planar.
 7. The measurement system of claim 4 where thehousing is a prosthetic component.
 8. The measurement system of claim 7where the prosthetic component is an insert.
 9. The measurement systemof claim 4 where the first support structure has a first region with afirst thickness and a second region with a second thickness, where thefirst and second thicknesses are different.
 10. The measurement systemof claim 4 where the surface of the first support structure is anarticular surface to support movement of the muscular-skeletal system.11. The measurement system of claim 4 further including a load platehaving a major surface between the at least three sensors and thesurface of the first support structure, which is an articular surface,wherein the internal major surface of the first structure couples to themajor surface of the load plate.
 12. The measurement system of claim 11wherein the electronic circuitry and the at least three sensors underliethe load plate.